Answer:
x=7y+10
Step-by-step explanation:
x−7y=10
x−7y+7y=10+7y
x=−7y+21/2
12/2 is a fraction
2x+14y=21
2x+14y+−14y=21+−14y
2x=−14y+21
2x2=−14y+21/2
7 (5) + 1 = 35 + 1 = 36
So, f(5) = 36
3.5