The total weight of a toy car and a flying saucer is 3.3 kg. The total weight of a toy car and a toy plane is 5.2 kg. If the total weight of a toy plane and a flying saucer is 5.48 kg, find the total weight of the toy car, the flying saucer and the toy plane.
Let 1 toy car be 1 T.
Let 1 flying saucer be 1 F.
Let 1 toy plane be 1 P.

1 T + 1 F = 3.3 --- (1)
1 T + 1 P = 5.2 --- (2)
1 P + 1 F = 5.48 --- (3)

(1) + (2) + (3)
1 T + 1 F + 1 T + 1 P + 1 P + 1 F = 3.3 + 5.2 + 5.48
2 T + 2 F + 2 P = 13.98
2(1 T + 1 F + 1 P) = 13.98 

1 T + 1 F + 1 P = 13.98 ÷ 2
1 T + 1 F + 1 P = 6.99

 Total weight of the toy car, the flying saucer and the toy plane = 6.99 kg

Answer(s): 6.99 kg