SOLUTION: how do you do this one....i have tried to come up with the equations and have had no luck for the prob. you have to put it into a pair of linear equations in two variables then

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Question 313128: how do you do this one....i have tried to come up with the equations and have had no luck
for the prob. you have to put it into a pair of linear equations in two variables then solve the equations using elimination or substitution..
Mrs. Boyd has a desk full of quarters and nickels. if she has a total of 25 coins with a total face value of 2.85 how many nickels would she have?

Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
Mrs. Boyd has a desk full of quarters and nickels.
n = no. of nickels
q = no. of quarters
:
"if she has a total of 25 coins"
n + q = 25
q = (25-n); use this form for substitution
:
" with a total face value of 2.85"
.05n + .25q = 2.85
:
Substitute (25-n) for q
.05n + .25(25-n) = 2.85
.05n + 6.25 - .25n = 2.85
.05n - .25n = 2.85 - 6.25
-.20n = -3.40
n =
n = +17 nickels
:
:
Check solution finding the total value; 25 - 17 = 8 quarters
.05(17) + .25(8) =
.85 + 2.00 = 2.85; confirms our solution of n=17