Question

HELP ASAP PLS!!!

Zachary purchased a computer for $1,400 on a payment plan. Two months after he purchased the computer his balance was $1,100. Four months after he purchased the computer, his balance was $800. What is an equation that models the balance y after x months?
The equation
models the balance y after x months:

Answer 1

Zachary pays $150 per month for his computer

Explanation:

after 2 months:

2x + 1100y = 1400..... equation 1

after 4 months:

4x + 800y = 1400...... equation 2

we can either multiply equation 1 by 2 or we can divide equation 2 by 2, the purpose is simply to get the x values equal so it can be eliminated from the equation.

dividing equation 2 by 2:

2x + 400y = 700 ...... equation 3

Now equation 1 minus equation 3:

0x + 700y = 700

700y = 700

y = 700/700

y = 1

substituting y=1 into equation 3

2x + 400(1) = 700

2x = 700 - 400

2x = 300

x = 300/2

x= 150

Therefore it is concluded that Zachary has a payment plan where he pays $150 each month for the computer