Dollar Bills and system of two linear equations
by Kendall Whiteside
(Happy Valley, Oregon)
“A student has some $1 bills and $5 bills in his wallet. He has a total of 15 bills that are worth $47. How many of each type of bill does he have? ”
Let x be the number of $1 bills and y be the number of $5 bills.
The number of $1 bills plus the number of $5 bills equal 15 or x + y = 15
Worth of $1 bills plus worth of $5 bills = $47 or 1x + 5y = 47
Therefore, just solve the system of equations below.
x + y = 15 (1)
x + 5y = 47 (2)
(2) minus (1) will give 4y = 32
y = 8 since 4 × 8 = 32
x + 8 = 15
x = 7
The student has seven $1 bills and eight $5 bills.
Click here to post comments
Join in and write your own page! It's easy to do. How? Simply click here to return to Algebra word problems.
Apr 02, 20 12:05 PM
Find out how to become an operations research analyst if you have a math major.
New math lessons
Your email is safe with us. We will only use it to inform you about new math lessons.