Answer:
24
Step-by-step explanation:
You should draw a picture to let everything fall into place:
.................2x.......................
N ----x+7------ O ---10---- P
Then you can easily see that
x+7 + 10 = 2x
17 = 2x - x
so x = 17
NP = 2x = 2*17 = 34
NO = x+7 = 17+7 = 24
OP = 10
NO + OP = 24 + 10 = 34 = NP
