How much galons are equivalent to are equivalent to 72 points

7x+8y=-18, 4x-9y=-3 solve the system of equations

How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid in order to get a 40% solution of acid?

Find the power set of each of these sets, where a and b are distinct elements. a) {a} b) {a, b} c) {1, 2, 3, 4} show steps