Determine the quadratic function given the graph​

Can someone me with this problem i don't understand i need

What are the solutions of the system? solve by graphing. y = -x^2 -6x - 7 y = 2

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