Final answer:
The jetliner cruised 240 miles when it used 1,200 gallons of fuel.
Step-by-step explanation:
To find the number of miles the jetliner cruised when it used 1,200 gallons of fuel, we can set up a proportion using the given information. The proportion would be:
12 miles / 60 gallons = x miles / 1,200 gallons
To solve for x, we can cross-multiply and then divide:
12 * 1,200 = 60 * x
14,400 = 60x
Dividing both sides by 60 gives us:
x = 14,400 / 60 = 240
Therefore, the jetliner cruised 240 miles when it used 1,200 gallons of fuel.