Answer
$x^{30}y^{10}$
Work Step by Step
RECALL:
(1) $(ab)^m=a^mb^m$
(2) $(a^m)^n=a^{mn}$
Use rule (1) above to obtain:
$(x^3y)^{10}=(x^3)^{10}y^{10}$
Use rule (2) above to obtain:
$=x^{3(10)}y^{10}
\\=x^{30}y^{10}$