Plsss help I’ll give u brainlest and 10 points number 13 pls

Is the square root of 4 plus the square root of 16 rational?

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?

The sum of a number and 5 times the number is 18.find the number