Which expression has a negative value? 07+3(-4X2) 0 -2[ 12-(-3) ] o (15-7) – (9-3) 0 -6[7+(-14)] – 30 HOW! help​

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