Question 76731
{{{(5ay+15a)+(-xy-3x)}}} Group the common terms
{{{5a(y+3)-x(y+3)}}} Factor out a 5 out of the first group, and factor out a -x out of the 2nd group.
{{{(5a-x)(y+3)}}} Notice we have like terms of (y+3). Combine these like terms. This is your answer. Notice if we foil the answer we get our problem again

{{{(5a-x)(y+3)=5ay+15a-xy-3x}}}