Answer:
8 units
Explanation:
here's your solution
=> let the length of rectangle be X
=> then width = x - 7
=> area = 8units
=>> area = length*width
=> area = x (x-7) = 8
=> x^2 - 7 = 8
=> now, x^2 - 7x - 8 = 0
=> factories the above equation by middle term split
=> x^2 - 7x - 8
=> x^2 - 8x + x - 8
=> take the common
=> x(x - 8) + 1(x - 8)
=> (x + 1) (x - 8)
neglect (x + 1) because this will in negative for X
=> x - 8 = 0
=> x = 8
=>so, x = 8
=>length = 8 units