Question 1061988
Let x= number of dimes
Let y=number of nickels

x+y = 24
10x + 5y = 210
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multiply top eqn by 10:
10x+10y = 240
Subtract 2nd eqn:
-10x-5y = -210
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0x + 5y = 30

y = 30/5 = 6
x = 24-6 = 18
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Ans:  18 dimes and 6 nickels
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Check:  18x10+6x5 = 180+30 = 210 (ok)