You would multiply the 3[tex]w^{2}[/tex] to every term giving you,
12[tex]w^{5}[/tex][tex]x^{2}[/tex] + 6[tex]w^{4}[/tex]x + 15[tex]w^{3}[/tex][tex]x^{2}[/tex]
(Note that when multiplying a squared root number, you add the the exponents together. Also a term/number without an exponent is understood to have a 1 as the exponent, it is just not written)
