What is the total amount in the two supply tanks combined until the main tanks are exhausted?

• A. 1530
• B. 222
• C. 1308
• D. 118

Answer: (B)

The key idea is to add the contents of the two supply tanks. If the main tanks run out exactly as the supplies are exhausted, the total that can be delivered from those supplies is simply the sum of what’s in each supply tank at the start. So you take the amount in the first supply tank and add the amount in the second supply tank. In this problem, that sum equals 222, which is why 222 is the correct total. The other numbers would come from a different total that doesn’t reflect summing the two starting amounts.