Question 1080827
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Let N be the number of nickels and Q be the number of quarters.
Then the number of dimes is 2N.

Nickels contribute  5N             cents to the total.
Dimes contribute   10*(2N) = 20N   cents to the total.
Quarter contribute  25Q            cents.

Hence, the "value" equation is 

5N + 20N + 25Q = 650   cents,   or

25N + 25Q = 650,    or

N + Q = 26,

The "coins" equation is 

N + 2N + 5Q = 58,   or

3N + 5Q = 58.           


So, you have this system

 N +  Q = 26,     (1)
3N + 5Q = 58.     (2)


The setup is done.
Solve the system by any method you know (substitution, elimination).
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