Can I have help plz I really need help on this one

2. explain in words how you plot the point (4, −2) in a rectangular coordinate system.

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

20 ! brainliest ! add and simplify your answer.