SOLUTION: philip has 40 coins in a jar and they are 10 cent, 20 cent or 50 cent pieces/ if their total value is $8.40 and he has one more 50 cent coin that 20 cent coins, how many of each ty

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Question 1072899: philip has 40 coins in a jar and they are 10 cent, 20 cent or 50 cent pieces/ if their total value is $8.40 and he has one more 50 cent coin that 20 cent coins, how many of each type does he have?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
x, y, z, the number of 10 cent, 20 cent, 50 cent coins

system%28x%2By%2Bz=40%2C10x%2B20y%2B50z=840%2Cz-y=1%29

system%28x%2By%2Bz=40%2Cx%2B2y%2B5z=84%2Cz-y=1%29


Sub for z
system%28x%2By%2By%2B1=40%2Cx%2B2y%2B5y%2B5=84%29

system%28x%2B2y=39%2Cx%2B7y=79%29
Subtract first from second equation
5y=40
highlight_green%28y=8%29----------the 20 cent coin count

You can find the other two coin quantities.