Please urgent i beg for help will mark brainlist

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 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

Subject: geometryneed with 6 and 7