Question

Jack wants to save up money to buy his math teacher a new calculator for the holidays.After 4 weeks, he has $78 saved up. After 9 weeks, he has $138.How much money does Jack save per week?

Answer 1

Answer:

$12 per week

Explanation:

Let the time taken to save up the money be "x"

Let the amount saved up be "y "

If after 4 weeks, he has $78 saved up, this can be written in a coordinate form as (4, 78)

Similarly, if after 9 weeks, he has $138, this is written in a coordinate form as (9, 138)

To get the amount Jack saved per week, we will have to take the unit rate as shown below:

$\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1} \\ m=\frac{138-78}{9-5} \\ m=\frac{60}{5} \\ m=12 \end{gathered}$

This shows that the amount of money that Jack save per week is $12 per week