Question

Zachary purchased a computer for 1800 on a payment plan. Three months after he purchased the computer, his balance was 1350. Five months after he purchased the computer, his balance was 1050. What is an equation that models the balance b after m months. What does the slope signify is zacharys equation?

Answer 1

If we notice, the decrease in payment after 3 and 5 months, it is a multiple of 150.

So, the equation that models balance b after m months is:

b = 1800 - 150m

Here, - 150 is the slope and it indicates the amount being decreased every month.

Answer 2

balance (b) = 1800 - 150m, where "m" is the number of months.

Explanation:

Zachary purchased a computer for 1800 on a payment plan.

After 3 months, his balance = 1350

Reduced amount = 1800 - 1350 = 450

So, 1 month payment = 450 ÷ 3 = 150

After 5 months, his balance = 1050

The reduced amount = 1800 - 1050 = 750

So, 1 month payment = 750 ÷ 5 = 150

Therefore, the rate of change = -150. It is negative because the amount getting reduced.

Therefore, the model is

balance (b) = 1800 - 150m, where "m" is the number of months.