Aviva has a total of 56 coins, all which are either dimes or nickels. The total
value of the coins is $5.05. Find the number of each coin?
Let the number of nickels be x
Then the number of dimes, using
ONE PART = TOTAL MINUS OTHER PART,
is 56-x.
Value Value
Type Number of of
of of EACH ALL
coin coins coin coins
-------------------------------------------
NICKELS x $0.05 $0.05x
DIMES 56-x $0.10 $0.10(56-x)
-------------------------------------------
TOTALS 56 ----- $5.05
The equation comes from the column on the right
0.05x + 0.10(56-x) = 5.05
Get rid of decimals by multiplying every term by 100
5x + 10(56-x) = 505
5x + 560 - 10x = 505
-5x + 560 = 505
-5x = -55
x = 11 = the number of nickels
The number of dimes is 56-x or 56-11 or 45 dimes.
Checking: 11 nickels is $0.55 and 45 dimes is $4.50
And indeed $0.55+4.50 = $5.05.
Edwin