Please answer this question

How to solve it and what thw answer is

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

1-for what value of x is line a parallel to line b 2-for what value of x is line a parallel to line b