Suppose that f(pi/3)=4 and f'(pi/3)=-2, and let g(x)= (cosx)/f(x). find g'(x) (pi/3)

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