Given f(x)=x^2-6x+8 and g(x)=x-2, solve f(x)=g(x) using a table of values

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