7*y*x 12*y*x x + ----- + 3*x - ------ 3 9
x + 7*y*x/3 + 3*x - 12*y*x/9
1*(x + 0)*(y + 4)
(1*(x + 0))*(y + 4)
x*(4 + y)
4.0*x + 1.0*x*y
4*x + x*y
108*x + 27*x*y -------------- 27
(108*x + 27*x*y)/27