12.96 cubic yards.
There are 3 feet in a yard, so 2 yards is 6 feet.
280 cubic feet = about 1,744 Imperial gallons OR 2,095 US gallons.
You may have mis typed your question. 1540 hundred cubic feet = 1540 cubic feet of course 154000 cu ft = 57.0 cu yards = 4361 Mega liters
408 yards = 1224 feet.
There are 3 cubit feet in 1 cubit yard. Although irrelevant in this context, you may wish to know that 1 cubit = 1.5 feet = 0.5 yards.
First, you need to calculate the volume to be filled with concrete. Say the footer is 12" wide and 8" in height and 21 feet long. ( I picked these numbers simply to make the following arithmetic easier for me) First, change the width and height to feet. 12" = 1 ft 8" = 0.67 ft. Volume, the, = 1 ft x 0.67 ft x 21 feet = 14 cubic feet. But you wanted the volume in "yards" which is really cubic yards. To convert our cubi feet of 14 to cubic yards, simply divide it by 27. ("27" = 9ft x 9ft x 9ft, which is a cube that contains 1 cubic yard.) So, to finish up, 14 cubic feet/27 cubic feet = a little more than 1 1/2 cubic yards, so you had better order 1 5/8 cubic yards of concrete. Most places only sell by the full cubic yard, so you will have to order 2 cubic yards. Some places only sell a complete truck full, so you will have to order 8 or 10 cubic yards . . . $ that is expensive! $ You may be able to share a load with a different customer. Or, of course, you may need several trucks full . . .
There are 3 feet in a yard. That gives you 466.67 yards.
7560 cubic yards of air 30 x 28 x 9 = 7560