SoMEONE PlZ HElP I DONT UNdERSTAND

(also i did not mean to pick math as the subject sorry)

How do you solve a question like this?

Prove that 16^4-2^13-4^5 is divisible by 11.

Acentral angle measuring 160 degrees intercepts an arc in a circle whose radius is 4. what is the length of the arc the circle formed by this central angle? round the length of the arc to the nearest hundredth of a unit. a) 4.19 units b) 6.28 units c) 12.57 units d) 12.57 square units