Please answer the 2 questions if you can? (This is my math from 8th grade)

Pranza plotted point a in the coordinate plane below.

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

If p(a) = 0.70 and p(b) = 0.20, then a and b are independent events if