Question 986085: Robert has 50 coins each 5 cents and 10 cents pieces which add up to 3.50 using an equation find how much of each type of coins there are? Answer by macston(5194) (Show Source):
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N=number of 5 cent coins; D=number of 10 cent coins
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N+D=50
D=50-N Use this to substitute for D.
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0.05N+0.10D=3.50 Substitute for D from above.
0.05N+0.10(50-N)=3.50
0.05N+5.00-0.10N=3.50
-0.05N=-1.50
N=30 ANSWER 1: There were thirty 5 cent coins.
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D=50-N=50-30=20 ANSWER 2: There were twenty 10 cent coins.
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CHECK:
0.05N+0.10D=3.50
0.05(30)+0.10(20)=3.50
1.50+2.00=3.50
3.50=3.50
