If Betty has  in her wallet and buys a sandwich that costs , the best way to determine how much money is left in her wallet is to subtract  from . 

An easy way to do this is to first subtract  and . This results in: . 

Next,  should be subtracted from . This results in: 

Therefore, Betty will have  left in her wallet. 

1. Find the equation from this scenario:

Since Bobby makes $12 an hour, you know that your slope is 12 because his total pay will be the $12 multiplied by the number of hours he worked.

Add the $5 daily bonus Bobby makes, which is your y-intercept in this equation.

Total = $12(hours) + $5

2. Find his total pay for 5 hours using the above equation:

$65 

We can determine Tom's weekly income by multiplying $50 into the 5 days he worked.  

Tom makes $250 a week.

 In four weeks, Tom makes $1000.

Since his rent was $1000 every four weeks, his net income is zero.

This is a simple interest rate problem, for which we use the formula:

Interest = P x r x t

P is the principal, or original loan amount; r is the annual interest rate; and t is the number of years in question.

In this problem we are given the interest ($100); the principal ($2,000); the interest rate (5%). We are asked to find t, the time in years it takes for $100 of interest to accumulate. We plug all these values into the formula and solve for t:

t is equal to 1 year. It will take 1 year for $100 of interest to accumulate.

To solve this problem, first you need to create a linear equation: . 

Divide both sides by :

.

.

Now, Anne can't buy .462 lollipops, so you round off to  Now you must calculate the money left over:

 .

So, Anne bought  lollipops and she has  left over. 

Create a linear equation to find your answer:

Since Jim makes 12 dollars per hour we can multiply 12 by the number of hours he worked. We then can multiply that number by the number of days he worked to get the total money earned.

Convert back into dollars, so you have .

To figure out how many minutes Mark can wash his car, we must understand the relationship between the total cost of a car wash and the length of the car wash. 

With every car wash, a fee of  is needed to dry the vehicle, so Mark will only have  remaining to spend on washing his car. If it costs  per minute to wash his car, we merely need to divide  by  to determine the number of minutes that Mark can wash his car:

Therefore, with Mark's , he can wash his car for  minutes.

In 4 weeks, Jamie will automatically be spending $300 on rent, so we will subtract this amount from whatever income Jamie makes.

In order to calculate her income, we will multiply $60 by 5, which equals $300.

Jamie makes $300 a week.

Then we will multiply this number by 4, since we are finding her net profit over 4 weeks. $300 times 4 equals $1200.

Lastly, we subtract her rent payment ($300) from her $1200 income, making her net profit $900.

To calculate how much money Samuel made this week, we will multiply how many cakes he made with how much profit he earns per cake. This week, Samuel made 25 cakes at $5 profit per cake, so we will multiply 25 by $5, which equals $125.

On top of this, we will add the $25 tip given to Samuel, which comes to a grand total of $150 earned this week. 

Landry rides 4 rides at the carnival, which cost $2 each. To determine their total cost, we will multiply 4 by $2, which equals $8.

Then we need to add the initial cost of entering the carnival, which is also $8. Adding these together, we find that Landry spent $16 at the carnival.