Let x = # of $8 tickets and y = # of $12 tickets. Then the number of $6 tickets is (x+y+280). The "items" equation is (x + y + 280) + x + y = 840, (1) The "value" equation is 6(x+y+280) + 8x + 12y = 6080. (2) Simplify 2x + 2y = 560 (560 = 840-280) 14x + 18y = 4400 (4400 = 6080-6*280) Or even better x + y = 280 7x + 9y = 2200. Solve by any method you know (substitution, elimination).