Example of Word Problems Involving Money:

A collection of coins consists of nickels, dimes & quarters. The number of quarters is double the number of nickels, and the number of dimes is five more than the number of nickels.  If the total amount of money is $5.05, how many of each kind of coin are in the collection?

Solution:

Step 1. Let x = Number of Nickels

Step 2. Then,

2x = Number of Quarters

x + 5 = Number of Dimes

Step 3. Total Value = (Number of Nickels)(Value of a Nickel) + (Number of Dimes)(Value of a Dime) + (Number of Quarters)(Value of a Quarter)

$5.05 = (x)($0.05) + (x + 5)($0.10) + (2x)($0.25)

 Step 4. Solving for x:

$5.05 = (x)($0.05) + (x + 5)($0.10) + (2x)($0.25)

$5.05 = $0.05x + $0.10x + $0.50 + $0.50x

$5.05 = $0.65x + $0.50

$0.65x = $5.05 - $0.50

$0.65x = $4.55

x = $ 4.55/$0.65

x = 7

Solving for the other unknowns:

2x = 2(7)

2x = 14

x + 5 = 7 + 5

x + 5 = 12

Answers:       

Number of Nickels      = 7

Number of Dimes       = 12

Number of Quarters    = 14

Step 5. The number of quarters is twice the number of nickels.

2(7) = 14

The number of dimes is five more than the number of nickels.

7 + 5 = 12

The total value is $5.05.

7($0.05) + 12($0.10) + 14($0.25) =

$0.35 + $1.20 + $3.50 = $5.05

Thus, the answers check.