①15a³+10a²
=5a²(3a+2)
②12abc-3bc²
=3bc(4a-c)
③6p(p+q)-4q(p+q)
=2(p+q)(3p-2q)
④m(a-3)+2(3-a)
=m(a-3)-2(a-3)
=(a-3)(m-2)