Answer:
KL = 9
Step-by-step explanation:
(7 + x - 1)(x - 1) = 12²
(x + 6)(x - 1) = 144
x² -x + 6x - 6 = 144
reduce:
x² + 5x -150 = 0
(x + 15)(x - 10) = 0
x = -15, x = 10
KL = 10 - 1 = 9
