U=3a-1
solve the equation for the indicated variable: a

First, you would start off by adding the 1 to the u, to get the 3a by itself. then, the equation you would have left would be u-1=3a. to get the a by itself, you want to divide by 3 because dividing is the opposite of multiplying, which is what you were doing with the 3a. then, you should get u-1 over 3 = a