Use the following:
HI = (1/2)(KL + MN)
5x + 2 = (1/2)(4x + 1 + 27)
5x + 2 = (1/2)(4x + 28)
5x + 2 = 2x + 14
5x - 2x = 14 - 2
3x = 12
x = 12/3
x = 4
However, the value of x is not the distance KL. We now evaluate KL at x = 4.
KL = 4x + 1
KL = 4(4) + 1
KL = 16 + 1
KL=17
The answer is choice D.