Please help me on this!

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

How do you use the elimination method for this question? explain, because i really want to understand!

Find the exact value of each of the following. in each case, show your work and explain the steps you take to find the value. (a) sin 17π/6 (b) tan 13π/4 (c) sec 11π/3