Suppose that the water level of a river is 34 feet and that it is receding at a rate of 0.5 foot per day. write an equation for the water level after a certain amount of days.

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