Question 167378
Juan has a jar containing eighty coins, all of which are either quarters or nickels. The total value of the coins is $14.60. How many of each type of coin does he have? 
:
Actually it is quite simple using two equations:
Let n =  no. of nickels
let q = no. of quarters
;
Total coin equation
n + q = 80
or
n = (80-q)
:
Total value equation:
.05n + .25q = 14.60
:
From the 1st equation, substitute (80-q) for n
.05(80-q) + .25q = 14.60
4 - .05q + .25q = 14.60
-.05q + .25q = 14.60 - 4
.20q = 10.60
q = {{{10.60/.20}}}
q = 53 quarters
:
I'll let you find the no. of nickels