Answer:
90 months
Explanation:
Let x = number of months
Let y = total cost of deal
Big City Nissan
y = 3000 + 420x - 840
⇒ y = 2160 + 420x
Rye Town
y = 3960 + 400x
Equate the equations and solve for x
2160 + 420x = 3960 + 400x
⇒ 420x - 400 x= 3960 - 2160
⇒ 20x = 1800
⇒ x = 90