Your piggy bank has a total of 18 coins in it; some are dimes and some are nickels. If you have a total of $1.40, how many nickels do you have?

Question

klimenkov · Answer

Let there be $x$ nickels and $y$ dimes. So we have 2 equations:
$$x+y=18$$$$5x+10y=140$$All you need is to solve this sytem.

anonymous · Answer

Could you tell me what's the worth of nickels and dimes?

anonymous · Answer

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anonymous · Answer

See, you are given with :

x + y = 18

Evaluate y from here by subtracting x from both the sides,

y = 18 - x

Now:

5x + 10 y = 140

5x + 10(18 - x) = 140

5x - 10x + 180 = 140

5x = 40

x = 8

So, he has 8 nickels..