#### Gretchen Vivanco

##### New member

- Joined
- Nov 6, 2006

- Messages
- 7

r = ab/a+b solving for a

I started with multiplying both sides by (a+b)

to get r(a+b) = ab

then distributed the r

ra + rb = ab

then subtracted rb from both sides

ra = ab - rb

then divided by r on both sides

a = ab - rb/ r

anyway, that's the wrong answer.

I know the answer is a = br/b-r (from the back of the math book), but I have no idea how they got it!!