Question 550874
A change purse contains a total of 100 nickels and dimes.
n + d = 100
n = (100-d)
:
 The total value of the coins is $7.
.05n + .10d = 7.00
replace n in with (100-d)
.05(100-d) + .10d = 7.00
5 - .05d + .10d = 7.00
-.05d + .10d = 7 - 5
.05d = 2
d = {{{2/.05}}}
d = 40 dimes
:
I'll let you find the number of nickels. check the solutions in the $$ equation

 
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