Find sum or difference.5/6 + 4/9a. 1/2b. 9/18c. 1 5/18d. 1 1/2

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