How do i write an algebraic expression for a) 4 times the difference of f squared and g, increased by the sum of f squared and 2g b) 3 times the sum of x and y squared plus 5 times the difference of 2x and y

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