A car travels 200 miles using 8 gallons of gas. At this rate, how many miles can the car travel on 12 gallons?

Method 1 (proportion): 200 miles / 8 gallons = x miles / 12 gallons; cross-multiply: 8x = 2400; x = 300 miles. Method 2 (unit rate): 200 miles ÷ 8 gallons = 25 miles per gallon; 25 × 12 = 300 miles. Both methods give the same answer. Fuel efficiency problems are common on the ASVAB and in real military contexts. Related calculations: (1) Cost per mile = total fuel cost ÷ miles driven; (2) Fuel needed for a trip = trip distance ÷ MPG; (3) Cost of a trip = trip distance × cost per mile. Example: trip of 450 miles in a vehicle that gets 25 MPG at $4/gallon: gallons needed = 450/25 = 18; cost = 18 × $4 = $72. The unit-rate method (find the per-unit value, then multiply) is often the most efficient approach to proportion problems and works for many real-world situations.