Let  be the number of pizzas made and sold. Each pizza will require $2 worth of ingredients, so the ingredients in total will cost . Add this to the cost to rent the equipment and the cost will be .

The pizzas will cost $4.50 each, so the money raised will be .

The profit will be the difference between the revenue and the cost:

The French club wants a profit of at least $500, so we set up and solve the inequality:

At least 300 pizzas must be made and sold.

The number of pounds of coffee beans totals 50, so one of the equations would be

.

The total price of the Kona beans is the unit price, $24 per pound, multiplied by the quantity,  pounds. This is  dollars. Similarly, the total price of the Ethiopian delight beans is  dollars, and the price of the mixture is  dollars. Add the prices of the Kona and Ethiopian Delight beans to get the price of the mixture:

These are the equations of the system.

Since Leslie has twice as many dimes as nickels, the number of nickels she has is half the number of dimes, or half of . This means she has  nickels. Also, since she has four more quarters than dimes, she has  quarters.

She has

 in nickels,

 in dimes, and

 in quarters.

In total, the number of dollars Leslie has is

Leslie has  dollars.

After John has ate 2 candies out of his total of 48 candies, he has 46 candies left.

25% of 46 is equivalent to:

However, candies are counted in units, which means if John could have only given 11 candies to charity if he said he has given almost 25% away.  The trick answer is 34 because 11.5 candies cannot be rounded to 12 candies.

Hence:

Let x be the cost of the phone before applying the 20% discount.  After applying the discount, the value will be equal to some amount y before applying tax.

After amount y has been taxed the 8.25%, the new value will be the price of the phone, which is $500.  The equation representing this relationship is:

We have a system of equations.  Substitute y in terms of x into the 2nd equation. Solving the value of x will give the original value of the phone.

Therefore, the price of the phone is approximately $577.37.

Every word problem has an unknown number. In this problem, the unknown number or value is the price of the shirt.  The variable  will represent the unknown number.  

In this problem,  will represent how much Mary spent for the shirt.  The problem states that $48 was $14 less than 2 times what she spent on for the shirt.   An equation will be written in order to solve this problem.

Then solve for .

The first step is to remove the subtraction of $14 by using the inverse operation, which would be addition.  Remember, because it is an equation, whatever operation you choose to perform on one side of the equation must also be done to the other side of the equation. Therefore, you will add $14 to both sides of this equation.

In order to solve for  , you will need to divide both sides by the coefficient, (the number next to the variable), which is 2.

This kind of question is really just a basic rate problem.  What it is asking is "How many months  at rate  does it take to make  birdhouses?"  The  rate is just the combination of the two men's rates:

Thus, you can set up the equation:

Thus, 

To solve this equation, first get everything into the same units.  Recall that there are ml for every one liter.  Thus,  liters are equal to  ml.  Now, what you basically have is a rate equation.  Recall that the total work is represented as follows:

For your data, the total "work" is the  ml.  Start by calculating the time as a decimal:

This gives you:

However, remember that this is in seconds.  You need to convert back to hours.  You do this by dividing by , giving you .  Rounding up, this gives you  hours.

This question could be set up like an equation as follows:

The variable  indicates the number of books that would have to be sold.  This comes out to:

Now, don't be tricked!  You can't sell partial books.  Thus, you will need to sell  books in order to turn a profit.  If you only sell , you will not have sold enough to make a profit.

This question is a bit hard.  You need to think it out step by step.  First, you could write an equation like this:

This represents the idea of trying to calculate when the profit per book will be three dollars.  Now, we know that profit is equal to:

Thus, you can rewrite your equation:

Now, the original cost is calculated by multiplying  by .  This is the same as .  The sales amount is just , where  indicates the total number of books sold.  This will also be the total for  in your equation.  Thus, you can write out the following equation:

Now, just solve for :

However, you will need to sell one more book than .  (That would be just a little too insufficient.)  Thus, the answer is .