Let x = amount of hazelnut (in pounds). Then the amount of mocha coffee is the same x pounds. Then the amount of vanilla-flavored coffee is (10-2x) pounds. The money equation is 12*(10-2x) + 13.50x + 15x = 138, or 120 - 24x + 28.5x = 138, 4.5x = 138 - 120 = 18 ====> x == 4 pounds. Answer. 4 pounds of hazelnut; 4 pounds of mocha coffee; and 2 pounds of vanilla-flavored coffee.