Answer:
The 36-pack is a better buy by $0.50 per 36 bottles.
Explanation:
24 bottles for $3 compared to 36 bottles for $4
Unit rates:
$3/24 = $0.125/bottle
$4/36 = $0.111/bottle
The 36-pack is a better buy since the unit price is lower.
$0.125 - $0.111 = $0.013888...
$0.01388888... * 36 = $0.50
Answer: The 36-pack is a better buy by $0.50 per 36 bottles.