Question 167692This question is from textbook Algebra structure and method
: sam has 30 nickles and dimes worth $2.40. How many nickles does he have?
This question is from textbook Algebra structure and method
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! sam has 30 nickles and dimes worth $2.40. How many nickles does he have?
.
Let n = nickles
and d = dimes
.
We have two unknowns, so we'll need two equations:
.
From: "sam has 30 nickles and dimes" we get equation 1:
n+d = 30
.
From: "worth $2.40" we get equation 2:
.05n + .10d = 2.40
.
Using "elimination method":
n+d = 30
.05n + .10d = 2.40
.
multiply the top equation by -.05:
-.05n - .05d = -1.5
.05n + .10d = 2.40
.
Add the two equations together:
-.05n - .05d = -1.5
.05n + .10d = 2.40
------------------------
.05d = .9
d = 18 (number of dimes)
.
Substitute the above into equation 1 to find n:
n+d = 30
n+18 = 30
n = 30-18
n = 12 (number of nickles)
|
|
|
