Answer:
3
Explanation:
The f^-1 notation indicates you need to find the inverse of the function
y=2x+1
x=2y+1
Exchange the x & y variables. Note this is what accomplishes that reflection across the line y = x
7=2y+1
-2y=1-7
-2y=-6
Divide both side of the equation by -2
negative divide negative is positive so
y=3