1) Let's apply the distributive property, factor 3 is going to be equally distributed as the GCD of that expression. Let's do it:
3(2x+4y+5z)
6x +12y +15z
2) So that's equivalent to that factored expression. Note that 3 is the GCD of 6,12,15. And the factored form allows us to deal with smaller coefficients.
