(x^3y^6)(10x^4y^8)(xy)=
\((x^3y^6)(10x^4y^8)(xy)=10x^{3+4+1}y^{6+8+1}=\boxed{10x^8y^{15}}\)
\((x^3y^6)(10x^4y^8)(xy) \\ \\ =10 x^{(3+4+1)} y^{(6+8+1)}=10 x^{8} y^{15}\)
