6xyz+10xyz
2a+3a
25ab-(-3ab)
5bc+(-5bc)
(4cd)(10cdx)
7abc-3abc
8am-3am
4xy-2xy
20xy/4xy
7mn+3mn
5a
0
2xy
10mn
40c^2d^2 x
28ab
16xyz
4abc
5xy
5am
