In the post-apocalyptic wasteland, 1 lizard is worth 8 bottle caps, 3 lizards are worth 5 gallons of water, and 1 horse is worth 80 gallons of water. Marla can scavenge for 20 bottle caps each day, but needs to pay 4 bottle caps per night for food and shelter. How many days does it take Marla to collect all the bottlecaps she needs to buy a horse?
Thoughts? Step-by-step reasoning:
First find how many lizards you get for one gallon of water: 3 lizards / 5 gallons = .6 lizards / gallon. Then figure out how many lizards 80 gallons of water is worth: 80 gallons * .6 lizards / gallon = 48 lizards. Then figure out how many bottle caps 48 lizards is worth: 48 lizards * 8 bottle caps / lizard = 384 bottle caps. Then figure out how many bottle caps Marla can save each day by subtracting the number she spends from the number she finds: 20 bottlecaps / day - 4 bottlecaps / day = 16 bottlecaps / day. Finally, divide the number of bottle caps Marla needs by the number she saves each day: 384 bottle caps / 16 bottle caps / day = 24 days.
Thus, the answer is 24.