The total weight of a toy rifle and a jigsaw puzzle is 2.6 kg. The total weight of a toy rifle and a toy car is 4.4 kg. If the total weight of a toy car and a jigsaw puzzle is 5.91 kg, find the total weight of the toy rifle, the jigsaw puzzle and the toy car.
Let 1 toy rifle be 1 T.
Let 1 jigsaw puzzle be 1 J.
Let 1 toy car be 1 C.

1 T + 1 J = 2.6 --- (1)
1 T + 1 C = 4.4 --- (2)
1 C + 1 J = 5.91 --- (3)

(1) + (2) + (3)
1 T + 1 J + 1 T + 1 C + 1 C + 1 J = 2.6 + 4.4 + 5.91
2 T + 2 J + 2 C = 12.91
2(1 T + 1 J + 1 C) = 12.91 

1 T + 1 J + 1 C = 12.91 ÷ 2
1 T + 1 J + 1 C = 6.455

 Total weight of the toy rifle, the jigsaw puzzle and the toy car = 6.455 kg

Answer(s): 6.455 kg