Send but 12 5 foot sections of fence to make a rectangular planting field. He wants as much as space as possible to plant vegetables. How should he arranged the fence? what is the greatest possible area of the planting field?

To maximize the planting space, the fence should be arranged in a rectangle with the longest sides running parallel to each other. This will ensure that the area enclosed by the fence is maximized.

To create a rectangle using 12 pieces of 5-foot fence, the dimensions should be 3 sides of 5 feet and 1 side of 6 feet. This will result in a rectangle with dimensions of 6 feet by 5 feet.

Therefore, the greatest possible area of the planting field would be:

Area = length x width
Area = 6 ft x 5 ft
Area = 30 square feet

So, the greatest possible planting field area would be 30 square feet.