The total weight of a water gun and a rubik's cube is 3.3 kg. The total weight of a water gun and a toy house is 5.8 kg. If the total weight of a toy house and a rubik's cube is 5.53 kg, find the total weight of the water gun, the rubik's cube and the toy house.
Let 1 water gun be 1 W.
Let 1 rubik's cube be 1 R.
Let 1 toy house be 1 H.

1 W + 1 R = 3.3 --- (1)
1 W + 1 H = 5.8 --- (2)
1 H + 1 R = 5.53 --- (3)

(1) + (2) + (3)
1 W + 1 R + 1 W + 1 H + 1 H + 1 R = 3.3 + 5.8 + 5.53
2 W + 2 R + 2 H = 14.63
2(1 W + 1 R + 1 H) = 14.63 

1 W + 1 R + 1 H = 14.63 ÷ 2
1 W + 1 R + 1 H = 7.315

 Total weight of the water gun, the rubik's cube and the toy house = 7.315 kg

Answer(s): 7.315 kg