Answer:
[tex]\huge \boxed{23}[/tex]
Step-by-step explanation:
QR < LM < ST
LM is the middle segment, it is in between the length of QR and ST.
LM is also the average or mean of QR and ST.
(QR+ST)/2 = LM
(3x+31)/2 = 8x-17
Multiply both sides by 2.
(2)(3x+31)/2 = (2)8x-17
3x + 31 = 16x - 34
Subtract 16x and 31 from both sides.
3x + 31 - 16x - 31 = 16x - 34 - 16x - 31
-13x = -65
Divide both sides by -13.
(-13x)/-13 = -65/-13
x = 5
Substitute x = 5 for LM.
8(5) - 17
40 - 17
= 23
