Answer
See below.
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 $_nC_rx^{n-r}y^r$.
Thus if the exponent on $(a+b)$ is $n$, then by what we learned, there are $n+1$ terms in the binomial expansion.
