7b + 3, -4b + 5, and -3b + 2

10b + 2
10
0
b - 8

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