What is the 3rd term of the sequence 4n-1?

Can someone check my answer? you : )

The following frequency table relates the weekly sales of bicycles at a given store over a 42-week period.value01234567frequency367108521(a) in how many weeks were at least 2 bikes sold? (b) in how many weeks were at least 5 bikes sold? (c) in how many weeks were an even number of bikes sold?

What is the gcf of 20c^3-5c^4+30c^6