Make sure if these are right

If x = 12 and y = 3, what is the value of x - y 2? 81 6 3 18

Aculture started with 4,000 bacteria. after 5 hours, it grew to 5,200 bacteria. predict how many bacteria will be present after 19 hours. round your answer to the nearest whole number.

Iknow its nothing to do with education, but what type of thing should i wrote here? ? : ) its for mcdonald's btw.