How do you know when to move the number to the left or the right.

For example
(x-5)/(x+8)=5/7 or
(y-2)/(y+2)=3/7

2 answers

What are you trying to do? Solve for the unknown (x or y?)

First get rid of the fractions that have the unknowns in the denomimator. It is not a question of moving right or left.

In the first case,
7(x-5) = 5(x+8)
7x -35 = 5x + 40
2x = 75
x = 37.5
I know the first problems answer is 2/75 and the second is 5 and in both cases I seem to mess up on the last part of moving the numbers like for instance in the 2/75 I first had the answer of 75/2 I had the numbers right but the wrong placement and the same with the other I first had 4/20 instead of 20/4 which equals 5 so I need to know how do you know which way to move the number to the left or the right?