<PRE><B>Question 185976</B>
suppose there are  N  nickels  and  D  dimes.
N + D = 106  (There are 106 coins in all.)

1 nickel = 5 cents.
1 dime   = 10 cents.

5*N + 10*D  =  840    ($8.40  =  840 cents)

N + D = 106  -------(1)
N = (106 - D)
5*N + 10*D  =  840  ---------(2)
5*(106-D) + 10*D = 840
530 - 5*D  + 10*D  = 840
5*D = 840 - 530
5*D = 310
D = 310/5 = 62
Eq(1)  N + D = 106  
       N + 62 = 106
       N  = 106 - 62
       N  = 44
Then , there are 62 dimes , 44 nickels.  Ans. 
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