Question 1150219
f(x) = mx + b


5f(x) = 5mx + 5b


f(5x) + 5 = [5mx + b] + 5


they're equal when 5mx + 5b = 5mx + b + 5
5mx cancels out and you are left with:
5b = b + 5
subtract b from both sides to get:
4b = 5
solve for b to get:
b = 5/4