Answer:
He would pay $4,320 back
Step-by-step explanation:
If he pays $120 a month then
$120 x 12 (12 months in a year)
$1440 x 3 = $4,320
He would have to pay $1,320 extra for the car. I wouldn't be willing to buy the car.
V= x*(10-2x)(8-2x)
for greatest volume, differentiate v w.r.t x and equate to 0,
dv/dx= (10-2x)(8-2x) + x(-2)(8-2x)+ x(10-2x)(-2)=0
you get x from solving the quadratic equation. volume will be max at that x
See picture for the answer.
