Question 980705
S=number of skate rentals; B=number of bike rentals
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S+B=25
B=25-S Use this to substitute for B.
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$15S+$20B=$450 Substitute for B from above.
$15S+$20(25-S)=$450
$15S+$500-$20S=$450
$500-$5S=$450 Add $5S to each side.
$500=$450+$5S Subtract $450 from each side.
$50=$5S Divide each side by $5.
10=S ANSWER 1: There were 10 skate rentals.
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B=25-S=25-10=15 ANSWER 2: There were 15 bicycle rentals.
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CHECK:
$15S+$20B=$450
$15(10)+$20(15)=$450
$150+$300=$450
$450=$450