SOLUTION: If operation 'o' is unknown and, a 'o' b = a + 2b ; and, 3 'o' X = 4 ; what is variable X? I would just like the first steps to solving this equation because it's been a while

Algebra ->  Expressions-with-variables -> SOLUTION: If operation 'o' is unknown and, a 'o' b = a + 2b ; and, 3 'o' X = 4 ; what is variable X? I would just like the first steps to solving this equation because it's been a while       Log On


   

Question 418611: If operation 'o' is unknown and, a 'o' b = a + 2b ; and, 3 'o' X = 4 ; what is variable X?
I would just like the first steps to solving this equation because it's been a while since I've done any math work. I took a placement test a week ago, and this question came up. I was kinda stumped. I've racked my brain ever since then to remember some formula to help me out but I can't seem to come up with one.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
If operation 'o' is unknown and, a 'o' b = a + 2b ; and, 3 'o' X = 4 ; what is variable X?
:
Assume the operation is multiply
ab = a + 2b
ab - a = 2b
a(b-1) = 2b
a = %282b%29%2F%28b-1%29
choose a convenient value for b, find a; b=2
a = %282%2A2%29%2F%282-1%29
a = 4%2F1
a = 4 when b = 2
:
:
Check this: 4 * 2 = 4 + 2(2)
therefore
3x = 4
x = 4%2F3
x = 11%2F3
:
There are probably other solutions, but this is one