Twenty-one fish are swimming in an aquarium. eleven are removed, leaving 10 fish. which number is the additive inverse of the number of fish left?

Me. i can't figure out this question. give an explanation too. .

Scott’s bank account showed a balance of $750 on sunday. during the next five days, he made one deposit of $140 and numerous withdrawals of $180 each. let x represent the number of withdrawals that scott made. write an inequality that can be used to find the maximum number of withdrawals that scott could have made and maintain a balance of at least $100. do not use a dollar sign ($) in your response.

Write an inequality for this description. - one fourth of the opposite of the difference of five and a number is less than twenty.