The table shows values for a quadratic function Picture

What is the average rate of change for this function for the interval from x=3 to x=5

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