Combine 5+7+15xy^2+9y^3+10x-13xy^2-3x-8y^3

Complete the solution of the equation. find the value of y when x equals to 1 9x-5y=29

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

Plzzz answer both questions and i will give you 100 points