Hi I need help on how to find the dimension of the box please

Question

The area of the sandbox is given by the relation A=8x²+18x+7. The owner planning to enlarge it by doubling the length and increasing the width by 3 units. What could be the possible dimension of the new sandbox?

I don't know this as the teacher did not discuss how to get it using this given equation

Answer 1

A = 8x^2 +18x + 7 = (4x+7)(2x+1)

double L by 2 increase W by 3

A= LW

so usually L>W then 4x+7 = L and 2x+1 = W

double L then means 2(4x+7)= 8x + 14

increase W by 3 means 2x+1+3 = 2x +4

new dimensions are 8x+14 by 2x+4