Set up a proportion:
2/7/7/8 = x/1
Multiply 1 to both sides:
(2/7 1)/(7/8) = x
(2/7)/(7/8) = x
Flip the 2nd fraction and multiply:
2/7 8/7
Multiply the numerators and denominators together:
16/49
So 16/49 tons of concrete are required to cover the entire wall.
