(1) There are two sizes of hot water bottles in the box. The big one can hold seven and the small one can hold four. To put 41 hot water bottles into the box, how many boxes are needed? (2) One yuan for 12 stamps, including four, eight and twenty cents. How many did you buy? Please solve all the equations

(1) There are two sizes of hot water bottles in the box. The big one can hold seven and the small one can hold four. To put 41 hot water bottles into the box, how many boxes are needed? (2) One yuan for 12 stamps, including four, eight and twenty cents. How many did you buy? Please solve all the equations

1. Let x big boxes, y small boxes, x, y are positive integers, 7 * x + 4 * y = 41, the solution is x = 3, y = 5. Answer: need 3 big boxes, 5 small boxes. 2. Let four buy x pieces, eight buy y pieces, two corner buy Z pieces, x + y + Z = 12,0.04 * x + 0.08 * y + 0.2 * z = 1, the solution is in line with the conditions of three groups: X1 = 2, Y1