If the system of equations 3x+y=a, 2x+5y=2a, has a solution (x,y) when x=2, compute a.
3x + y = a
2x + 5y = 2a.
Then the first equation x 2 = second equation.
6x + 2y = 2x + 5y
4x = 3y
So if x = 2, then y = 8/3.
Thus 3*2 + 8/3 = a = 26/3
The answer is actually 28/5, but thanks for your help.