Answer
$80x^2$
Work Step by Step
According to the Binomial Theorem we can obtain the $r+1$th term of the expansion of the binomial $(x+y)^n$ by the formula $_nC_rx^{n-r}y^r$.
Hence here it is: (by plugging in $n=5,r=3$ and $x,2$): $_5C_3(x)^{5-3}2^3=10\cdot x\cdot8=80x^2$
