The total weight of a toy plane and a jigsaw puzzle is 2.6 kg. The total weight of a toy plane and a toy house is 5.2 kg. If the total weight of a toy house and a jigsaw puzzle is 4.87 kg, find the total weight of the toy plane, the jigsaw puzzle and the toy house.
Let 1 toy plane be 1 T.
Let 1 jigsaw puzzle be 1 J.
Let 1 toy house be 1 H.

1 T + 1 J = 2.6 --- (1)
1 T + 1 H = 5.2 --- (2)
1 H + 1 J = 4.87 --- (3)

(1) + (2) + (3)
1 T + 1 J + 1 T + 1 H + 1 H + 1 J = 2.6 + 5.2 + 4.87
2 T + 2 J + 2 H = 12.67
2(1 T + 1 J + 1 H) = 12.67 

1 T + 1 J + 1 H = 12.67 ÷ 2
1 T + 1 J + 1 H = 6.335

 Total weight of the toy plane, the jigsaw puzzle and the toy house = 6.335 kg

Answer(s): 6.335 kg