It's like a CFA question.
Strictly speaking, the valuation of bonds depends on how you model interest rate term structure (ho-lee, HJM, or LIBOR etc.). But here I guess we assume the interest rate will be constant throughout the investment horizon. Plus, the convention is that bond pays semi-annual coupon at the rate of $(1 + C)^{0.5} - 1$ (or approx. $0.5C$), but here I just assume it pays once a year, at the rate of $C$ for simplicity.
So here is the answer (hopefully I got the numbers right, but even if not, you get how to do it):
$$1117.19 = \frac {1000}{(1+r)^n} + \frac{81}{(1+r)} + \frac{81}{(1+r)^2} + ... + \frac{81}{(1+r)^n}=\frac{1000}{(1+r)^n} + 81 \times \frac{(1+r)^n - 1}{(1+r)^n \times r}$$
$$981.32 = \frac{1000}{(1+r)^n} + \frac{65}{(1+r)} + \frac{65}{(1+r)^2}+...+\frac{65}{(1+r)^n}=\frac{1000}{(1+r)^n} + 65 \times \frac{(1+r)^n - 1}{(1+r)^n \times r}$$
let $x = \frac {1000}{(1+r)^n}$, and $y=\frac{(1+r)^n - 1}{(1+r)^n\times r}$, we have $$1117.19=x + 81 \times y$$
$$981.32=x+65 \times y$$
Solving x and y, we have:
$$\frac{1000}{(1+r)^n} =x= 429.348125$$
$$\frac{(1+r)^n - 1}{(1+r)^n \times r}=y=8.491875$$
Thus
$$(1+r)^n = 2.329112303$$
$$r=0.06719975=6.72\%$$
$$n=13$$