Provide the correct answer to the problem shown below

Me what is the value of x? showing work would be appreciated - ! : )

Melanie is buying a bathing suit that costs 39.99. she is given a discount at the cash register of $6.00 when she scratched 15% off on a game piece for a store promotion. what will the sale price of melanie’s bathing suit be?

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