- #1
LearninDaMath
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Homework Statement
Bob has 50 coins, all nickels and dimes, worth a total of 4.85. How many nickels does he possess?
Homework Equations
n + d = 50
5n + 10d = 485
Multiplying the first equation by 10, we obtain 10n+10d=500
Subtracting the second equation from the third equation, we get 5n=15, so n = 3
The Attempt at a Solution
I have the solution. My question is:
Why do you multiply the first equation by 10 to begin with? Also, why do you then subtract one equation from the other? What is the rationale to it?
Thanks in advance