Answer:
53°
Step-by-step explanation:
17² = 18² + 20² - 2(18)(20) cos Q
289 = 324 + 400 - 720 cos Q
289 = 724 - 720 cos Q
-435 = -720 cos Q
0.6042 = cos Q

Q = 52.83
FW = PW(1+i)^N
= $6900(1+0.039)^1
solve for FW
(sorry don't have a calculator on me rn)