[tex]\text{Solve for a:}\\\\p+q=2ab\\\\\text{Since we want to solve for a, it needs to be by itself}\\\\\text{To do this, we have to divide both sides by 2b}\\\\\frac{p+q}{2b}=a\\\\\text{Now since A it's by itself, that'll be your answer}\\\\\boxed{\frac{p+q}{2b}=a}[/tex]