Question 357564
a piggy that bank contains only nickels and dimes.
 The total value of the coins in Pete's bank is $2.75.
 If the nickels were dimes and the dimes were nickels, the total value of the
coins would be $3.25.
 Find the number of nickels:
:
Let n = no. of nickels
Let d = no. of dimes
:
Write an equation for each statement:
:
"The total value of the coins in Pete's bank is $2.75."
.05n + .10d = 2.75
:
"If the nickels were dimes and the dimes were nickels, the total value of the
 coins would be $3.25."
.10n + .05d = 3.25
:
Multiply the above equation by 2, subtract the 1st equation
.20n + .10d = 6.50
.05n + .10d = 2.75
-----------------------subtraction eliminates d, find n
.15n = 3.75
n = {{{3.75/.15}}}
n = 25 nickels
:
:
Check solution:
find d using the 1st equation
.05(25) + .10d = 2.75
1.25 + .10d = 2.75
.10d = 2.75 - 1.25
.10d = 1.50
d = {{{1.50/.10}}}
d = 15 dimes
:
Find the total using the 2nd equation
.10(25) + .05(15) =
2.50 + .75 = 3.25; confirms our solution