
now, the first one, on the far-left.... can't see the height.. but I gather you do, now as far as its Base area, well, the bottom is just a 12x12 square, so the area of its base is just 12*12
now, the middle pyramid, has a height of 6, the base is also a square, 8x8, so the Base area is just 8*8
now the last one on the far-right
has a height of 8, the Base is a Hexagon, with sides of 6
You have to simplify like this
(-5)(-8)=40
Time for first plane = 625 / 250
= 2.5 hours
after 1.25 hours
boeing 747 takes 1.25 hours (2.5 - 1.25) to arrive at the same location at the same time
so, speed = distance / time
= 625 / 1.25
= 500
the average speed of the boeing 747 is 500 mph