Which of these is the inverse of f(x)

(A) method A
to find the inverse of a function, we do the two following steps:
1. exchange x and y (or f^(-1))
2. Solve for y in terms of x.
For the given problem, 
y=3x-4
step 1: exchange x and y:  x=3y-4
step 2: solve for y:  x=3y-4 => 3y=x+4 => y=(x+4)/3 => f^(-1)=(x+4)/3

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post