Question 177081
*[tex \large 3x = 5y\]


Add *[Tex \large -5y\] to both sides


*[Tex \large 3x - 5y = 0\]  Done.


Standard form is *[Tex \large Ax + By = C\] and *[Tex \large 0\] is just as good a number for C as any other.  By the way, when you said 'no coefficient' you really meant 'no constant term.'  Each of the variables has a coefficient, namely 3 on the x and -5 on the y.  And the only reason you couldn't see the constant term is because it is zero -- but that doesn't mean it isn't there.