<p>Solve for a </p>
<p>x/a - y/b + z/c = 1</p>
<p>I got: a = (xbc - yac + zab) / bc</p>
<p>Am I right?</p>
<p>No. Unfortunately, you are wrong. First of all, remember that when you are told to solve for a, then the final expression can’t contain “a” itself. It must be made up of different variables.</p>
<p>The mistake you made was that you directly tried to make the denominator common for everything. Don’t do that. Transfer (y/b) and (z/c) to the RHS. This makes the expression</p>
<p>x/a = y/b - z/c</p>
<p>No, make the denominator on the RHS common for both terms. You’ll get</p>
<p>x/a = (cy - bz)/bc</p>
<p>Then, move “a” to the RHS and everything on the RHS to the LHS. The final answer will be</p>
<p>a = xbc/(cy-bz)</p>