How many gallons of a 50% antifreeze solution must be mixed with 80 gallons of 25% antifreeze to get a mixture that is 40% antifreeze

Three numbers x, y, and z are in the ratio 2: 7: 8. if 12 is subtracted from y, then three numbers form a geometric sequence (in the order x, y–12, z). find x, y, and z. there are 2 sets.