Please help! Tell me the numbers that I have to add to demostrate the answer

When a formula is solved for a particular variable, several different equivalent forms may be possible. if we solved a=1/2bh for h, one possible correct answer is h=2a/b . which one of the following is not equivalent to this? a. h= 2(a/b) b. h= 2a(1/b) c. h= a/1/2b d. h= 1/2a/b

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Ineeeeed this is due tomorrow and i dont know the answer can you find all the exponents