Line YZ is the midsegment of triangle QRS because it connects the midpoints of lines QR and RS. We would solve for x by appying the midsegment theorem which states that the midsegment is half the length of the third side or base. This means that
YZ = 1/2(QS)
x + 2 = 1/2 * (3x - 8)
2(x + 2) = 3x - 8
By opening the parenthesis, we have
2x + 4 = 3x - 8
Collecting like terms, we have
3x - 2x = 4 + 8
x = 12
Option C is correct