SOLUTION: A pile of 55 coins consisting of nickels and dimes is worth $3.90 . Find the number of each.

Question 1042922: A pile of 55 coins consisting of nickels and dimes is worth $3.90 . Find the number of each.
Found 2 solutions by Fombitz, rothauserc:
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
1.
and

2.
Subtract eq. 1 from eq. 2,

Now use eq. 1, to solve for D.

Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
let x be the number of nickels and y be the number of dimes
:
we have the following two equations in two unknowns
:
1) x + y = 55
2) .05x + .10y = 3.90
:
solve equation 1) for x and substitute for x in equation 2)
:
x = 55 - y
:
.05(55 - y) + .10y = 3.90
:
2.75 - .05y + .10y = 3.90
:
.05y = 1.15
:
y = 23
x = 32
:
*******************************
we have 32 nickels and 23 dimes
*******************************
:
we check this by substituting for x and y in equation 2)
:
.05(32) + .10(23) = 3.90
:
1.60 + 2.30 = 3.90
:
3.90 = 3.90
:
our answer checks :-)

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