Question 158114
A change maching contains nickels,dimes, and quarters. There are 75 coins in the machine, and the value of the coins is $7.25. There are 5 times as many nickels as dimes. Find the number of coins of each type in the machine.
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>>...There are 75 coins in the machine...<<

{{{N + D + Q = 75}}}

>>...the value of the coins is $7.25...<<

{{{.05N +.10D + .25Q = 7.25}}} 

We remove the decimals by multiplying through
by 100:

{{{5N+10D+25Q=725}}}

We can also simplify it further by dividing
through by {{{5}}}

{{{N+2D+5Q=145}}}


>>...There are 5 times as many nickels as dimes...<<

{{{N=5D}}}

So we have this system of equations:

{{{system(N+D+Q=75,N+2D+5Q=145,N=5D)}}}

Can you solve that system?  If not post again
asking how.

Solution:  

50 nickels, 10 dimes, 15 quarters

Edwin</pre>