18v7u6 can be factored as 32 x 2 x v7 x u6
27v2x8u5 can be factored as 33 x v2 x x8 x u5
Rmember that when you divide exponents you subtract one from the other.
Now we can see what they have in common: 32, v2, and u5.
The greatest common factor is 9v2u5.