Question 743190: I have tried but it has been way too long since i have done algebra. I can no longer even help a 5th grader with homework.
Mrs johnson is buying supplies for her fifth grade class. Mechanical pencils cost 15 cents each and markers cost 25 cents each. If she spends $21 on these items, and buys 100 items in all, how many pencils and how many markers did she buy?
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! The problem states:
Mrs johnson is buying supplies for her fifth grade class. Mechanical pencils cost 15 cents each and markers cost 25 cents each. If she spends $21 on these items, and buys 100 items in all, how many pencils and how many markers did she buy?
Let x = the number of mechanical pencils she bought
Let y = the number of markers she bought
We are given
.15x + .25y = 21.00
x + y = 100
and x= 100 - y
substitute for x in equation one and we have
.15(100 - y) + .25y = 21.00
15 - .15y + .25y = 21.00
.10y = 6 and y = 60, so x = 40
checking our work
.15*40 + .25*60 = 21
6 + 15 = 21
so she bought 40 mechanical pencils and 60 markers
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