Colby has $100. He buys five CD's that cost x dollars each, and then he buys three DVD's for y dollars each. Write an algebraic expression for the amount
of money he has remaining (in terms of x and y).

Serena is making an experiment. for that, she needs 20 grams of a 52% solution of salt. she has two large bottles of salt water: one with 40% and the other with 70% of salt in them. how much of each must she use to make the solution she needs? i am in need of