Use a number line to help represent the situation from the exercise.
B
Solve the expression created in Part A. Then compare the amount of money Kim has left to the price of the T-shirt.
A
45+(-17)+(-8)+(-4)
B
No, see solution.
Practice makes perfect
We want to write an addition expression that represents the amount of money Kim has left. We can use a number line to help us. From the exercise, we know that Kim has $45 to spend for the day at the zoo. Then she pays $ 17 for admission, $ 8 for lunch, and $ 4 for a snack. Let's list the steps we will follow to create a number line for this situation.
First, we start at 45, which represents the amount of money Kim starts with.
Next, we move 17 units to the left. This represents her paying for admission.
Then, we move 8 units to the left to represent her buying a lunch.
Finally, we move 4 units to the left for the snack.
Let's mark these steps on the number line.
As we can see from the graph, the sum of 45, - 17, -8, and -4 describes the situation from the exercise. Let's combine these integers into an addition expression to represent how much money Kim has left.
45+(-17)+(-8)+(-4)
We did it!
We want to know whether Kim has enough money left to buy a T-shirt for $ 19. Let's solve the expression we created in Part A to find out how much money Kim has left. We can then see if it's enough to buy the T-shirt. Let's take a look at the expression we wrote in Part A.
45+(-17)+(-8)+(-4)
We will solve the expression exactly as we would solve for the sum of two integers. Since we are adding integers with differentsigns, one positive and three negative, we need to subtract the absolute values of the integers. Let's take a look.
Kim has $16 left. This is a a positive amount of money Kim because |45| is greater than the sum of |-17|, |-8|, and |-4|. The T-shirt that Kim wants to buy is $19 dollars. Since 19 is greater than 16, and we can say that Kim does not have enough money left to buy the T-shirt.
