Solve for a in terms of b and c, assuming b≠3:
ab = 3a +2b + c.
ab = 3a + 2b + c subtract 3a from both sides
ab - 3a = 2b + c factor the left side
a (b - 3) = 2b + c divide both sides by ( b - 3)
a = [ 2b + c ] / [ [ b - 3 ]
Good job, QS.....!!!