Zachary purchased a computer for ​$1 200 on a payment plan. Two months after he purchased the​ computer, his balance was ​$920 . Five months after he purchased the​ computer, his balance was ​$500 . What is an equation that models the balance y after x​ months? Write in slope intercept form.

Respuesta :

y=kx+b.
for this question.
920=2k+b(function 1)
500=5k+b(function 2)
use function 2 - function 1, we get
-420=3k
k=-140

back to function 1

920=2*(-140)+b
b=920+280
b=1200

Thus, y=-140x+1200