Zachary purchased a computer for $1,500 on a payment plan. Four months after he purchased the computer, his balance was $880. Seven months after he purchased the computer, his balance was
$415. What is an equation that models the balance y after x months?
The equation
models the balance y after x months.
(Type your answer in slope-intercept form. Use integers or fractions for any numbers in the equation. Do not include the $ symbol in your answer.)