How do u do this I need help please help me

You receive 15% of the profit from a car wash how much money do you receive from a profit of 300

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

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