Question 53582
I'm assuming your equation is {{{x/(x+a)=b/a}}}.  To solve for x, we need to isolate it on one side of the equation -- it doesn't matter which side.  In order to that for our equation, we can just use means-extremes method, also known as cross-multiplying, instead of finding the LCD.  So, from cross multiplying, we get {{{ax=b(x+a)}}}.  Simplifying, we get {{{ax=bx+ab}}}.  Now just divide both sides by {{{a}}} and we get {{{x=(bx)/a+b}}}.