Final answer:
The football team's total yardage after three downs is a loss of 14 yards, calculated by adding the gains and losses of yardage from each down.
Step-by-step explanation:
The question from the student is asking about the total gain or loss of yardage by a football team during a series of downs. To calculate the total yardage, we need to consider the yards lost and gained. On the first down, the team loses 11 yards. On the second down, they gain 15 yards, and on the third down, they lose 18 yards. To find the total, we simply add the gains and losses together, keeping in mind that lost yards are negative.
So the calculation would look like this: -11 yards + 15 yards - 18 yards.
Adding these together gives us -11 + 15 - 18 = -14 yards. Therefore, the team's total yardage is a loss of 14 yards.