328 algebra De mystif ieD
- Let x = number of times Sharon uses her skates
The cost to rent skates is 3x.
60 3
60
3
20 20
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<
< or >
x
x
xx
Sharon would need to use her skates more than 20 times to justify
purchasing them instead of renting them.
- Let x = number of kilowatt-hours used per month
28 + 0.07x = monthly bill
28 007 210
28 28
007 182
182
007
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≤+
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≤
≤
≤
x
x
x
x 2600
The James family can use no more than 2600 kilowatt-hours per month
in order to keep their electricity costs within their budget.
- Let x = amount spent at the store annually
0.05x = extra 5% purchase charge per year
40 005
40
005
800 800
.
.
≤
≤
≤ or ≥
x
x
xx()
A shopper would need to spend at least $800 per year to justify the
$40 annual fee.
- Let x = annual sales level
0.08x = annual commission
15,000 + 0.08x = straight annual salary plus commission
15 000 00825000
15 000 15 000
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10 000
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125 000
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x
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