Expert: Richard J. Raridon - 10/23/2004

Question
I need your help with 4 problems that im having trouble understanding you have to solve and simplify each of the following step by step.

1. 4 over x = 5 over 7
2. 3a over 7 = -2 over 5
3. x+1 over 6= 4 over 3
4. 24 over x-3 = 72 over x+3

Answer
1. 4/x = 5/7
just cross multiply to get 28 = 5x so x = 28/5
2. 3a/7 = -2/5
3a = -14/5 so a = -14/15
3. (x+1)/6 = 4/3
3(x+1) = 24
3x +3 = 24
3x = 21, x = 7
4. 24/(x-3) = 72/(x+3)
divide each side by 24 to get 1/(x-3) = 3/(x+3)
now x+3 = 3(x-3)
x+3 = 3x-9
12 = 2x so x = 6