Two cities on the equator have longitudes of 72 E and 35w how do i find the distance between cities?

Divide the Earth's cirference by 360, and then multiply that by the difference in longitudes. The difference here is 72 + 35 = 107 degrees, because they are on opposite sides of 0 degrees longitude which runs through Greenwich England. So if the Earth's cirference is 24,000 (guess) then each line of longitude is 66.7 miles; that gives you an answer of 7,133 miles.