SOLUTION: Hi please help me. Three ducks and two ducklings weigh 77 kg Four ducks and three ducklings weigh 107 kg All ducks weigh the same and all ducklings weigh the same What is the we

Algebra ->  Equations -> SOLUTION: Hi please help me. Three ducks and two ducklings weigh 77 kg Four ducks and three ducklings weigh 107 kg All ducks weigh the same and all ducklings weigh the same What is the we      Log On


   

Question 370500: Hi please help me.
Three ducks and two ducklings weigh 77 kg Four ducks and three ducklings weigh 107 kg All ducks weigh the same and all ducklings weigh the same What is the weight of two ducks and one duckling?
(3D + 2d = 77)
(4D + 3d = 107)
Answer by Jk22(389) About Me  (Show Source):
You can put this solution on YOUR website!
We notice that 2xEqu1 - Equ2 (*) gives the weight of : 2 Ducks and 1 duckling

(6-4)D + (4-3)d = 2D + d = 2*77 - 107 = 140 + 14 - 107 = 33 + 14 = 47 kg


from 3m-4n = 2*(2m-3n) => m = -2n, hence the multiplier are 2, -1 for eqn 1 and 2 resp.