Question 178134
store sold 300 items total.
let x = number of hard drives sold
let y = number of cd drives sold
let z = number of floppy drives sold
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x + y + z = 300
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The store sold six times as many hard drives as they did CD ROM drives.
hard drives = 6 * cd drives meaning:
x = 6y
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store sold half as many floppy drives as hard drives. 
floppy drives = 1/2 * hard drives meaning:
z = x/2.
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with this information you should be able to reduce your equation to one unknown.
you have z = x/2.
this is your first substitution.
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you have x = 6y.
if you divide both sides of this equation by 6, you get:
y = x/6.
this becomes your second substitution.
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since all variables are now in terms of x, your equation becomes:
x + x/6 + x/2 = 300
multiply both sides of this equation by 6 to get:
6x + x + 3x = 1800
which becomes:
10x = 1800
which becomes:
x = 180
y = 180/6 = 30
z = 180/2 = 90
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your answer should be:
x = 180
y = 30
z = 90
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x + y + z = 300 becomes:
180 + 30 + 90 = 300 becomes:
300 = 300
which is true so the values for x,y,z are good.
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