marting1667 marting1667

23-05-2017
Mathematics

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A money box contains only 10-cent and 20-cent coins. There are 34 coins with a total value of $5.40. How many coins of each

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PHDFlopper PHDFlopper

23-05-2017

10x+20y=540
x+y=34
y=34-x

Plug in (34-x) for y:
10x+20(34-x)=540
10x+680-20x=540
-10x=-140
10x=140
x=14

There were 14 ten cent coins and 20 20 cent coins

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