Answer:
x = A(x) / 7
Explanation:
A rectangular shape screen has an area A(r) in square inches
A(r) = w * x where w is width and x is length
If we know A(r) and w = 7 in, we can express A(x) area of the rectangular screen as;
A(x) = 7*x ⇒ x = A(x) / 7