C is the correct answer. The equation for f(x) is f(x)=1.8x-10 and the equation for g(x) is g(x)=-4 . Since we're trying to find the input value for x where f(x)=g(x) make the 2 equations equal to each other and you'll get your answer.
Answer:
y x
-1 0
1 1
3 2
5 3
This is a table that follows the above function
-2m+15=45
-2m=45-15
-2m=30
2m=-30
m=-15