Question 49262
Try this:
For a rectangle, Area = Length X Width.

504 = (10x-24)(14) Simplify and solve for x.
504 = 140x - 336 Add 336 to both sides of the equation.
840 = 140x Divide both sides by 140.
6 = x

The length is:
L = 10x-24 = 10(6)-24 = 60-24 = 36 inches.

Area = (14)(36) = 504 sq.in.