Answer:
David: $50.00
Pam: $47.50
Explanation:
David:
first 10 lb $2 per lb
Additional lbs are $1
When buying 40 pounds:
first 10 lbs: $2 × 10 = $20
other 30 lbs: $1 × 30 = $30
total cost: $20 + $30 = $50.00
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Pam:
$10 entrance fee
first 10 lb $1.5 per lb
Additional lbs are $0.75
When buying 40 pounds:
Entrance: $10
first 10 lbs: $1.5 × 10 = $15
other 30 lbs: $0.75 × 30 = $22.5
total cost: $10 + $15 + $22.50 = $47.50