To find how much additional money Sarah would make by applying the discount, find the difference between her earnings in a normal month and a month where the discount is applied. In a normal month, multiply the normal price by the normal quantity sold to find the normal earnings:

To find earnings at the discounted price, first calculate how much each necklace will cost with the % discount. To do this, subtract the amount discounted (calculated by percent as a fraction of  multiplied by the original price) from the original price.

If  necklaces are sold at the new discounted price of  each, multiply these together to find the total earnings with the discount.

Finally, subtract the earnings without the discount from the earnings with the discount to find the additional money made by applying the discount.

The statement "A jar of Verde Salsa costs more than a jar of Rojo Salsa" can be tested by comparing the price per jar of each salsa.

 versus 

The statement is false since the price of Rojo per jar is greater. 

The remaining statements above can all be proven true or false by finding the price per ounce of each salsa.

Rojo Salsa is on sale at a price of  for  jars of  ounces each. The following operations can be used to determine the cost of Rojo Salsa per ounce:

 for Rojo Salsa.

Verde Salsa is on sale at a price of  for  jars of  ounces each. The following operations can be used to determine the cost of Verde Salsa per ounce.

 for Verde Salsa.

The only true statement is "An ounce of Rojo Salsa is the same price as an ounce of Verde Salsa."

To solve this word problem, set up an algebraic equation, putting  in for the unknown value of the second shirt. The equation is  because we know the cost of the two shirts will total .

To solve for , subtract  from each side. This results in .

Convert 15% to a decimal.

Let the original price equal . The discount will be 15% of . Subtracting the discount from the original price will equal the amount paid, $12.

Using this equation, we can solve for .

If this is a square fence, then each of the four sides will be equal.

The fence in question will become the perimeter of that square.

Since  when working with a square, for this problem .

First we need to find the area of the smaller rectangle. 

Now to find out how many can fit, we divide the total area by the smaller area.

However, the problem is asking how many WHOLE rectangles can fit. Therefore only  can fit.

First, use the information to find the total number of socks Eric has by setting up a proportion:

, where  is the number of total socks.

Once you cross multiply and divide, you will find that .

To find the number of white socks Eric has, subtract the number of black socks  from the total number of socks:

pure water and pure acid

In general, mixture problems have the form:

, where volume and percent

The equation to solve becomes:

Then the solution is .

The cost of mailing each invitation is .

To invite everyone, it will cost .

Then the change is .

Look for the verbal cues in the question.  IS translates to "equals" and OF translates to multiplication. 

Thus the equation to solve becomes: