Answer:
280 yards * 3 feet/yard = 840 fee
Explanation:
since the fencing is sold by the foot, we need to convert the given 280 yards to feet in order to determine how much fencing the farmer should buy.
To convert yards to feet, we multiply the number of yards by 3, since there are 3 feet in 1 yard.
280 yards * 3 feet/yard = 840 feet
Therefore, the farmer needs to buy 840 feet of fencing for his new grazing field.