I would solve every problem like that the same way. Multiply both sides by the denominator in the LHS, collect terms with a variable in the LHS, collect constant terms in the RHS, combine like terms, and multiply by the reciprocal of the resultant coefficient on the variable.
Next time don't try to get fancy by drawing a vinculum; they never render properly anyway. Enclose your numerator in parentheses, type a forward slash, and then enclose your denominator in parentheses:
(3x)/(2x + 7) = 36
is the desired rendering. It means exactly the same thing as:
