Answer:
10
Step-by-step explanation:
The two marked angles are a linear pair, so have a sum of 180°.
(2m +10) +(5m +100) = 180
7m +110 = 180 . . . . . . . collect terms
7m = 70 . . . . . . . . . . . . subtract 110
m = 10 . . . . . . . . . . . . . divide by 7
