Answer:
4 3/4 yards
Step-by-step explanation:
convert ft to inches
12 ft = 12*12 = 144 inches
21 ft = 21*12 = 252 inches
height (thickness) is 6 inches
convert to yards
1 yard = 36 inch
width
1/36 = x/144
x=4 yards
length
1/36 = x/252
x=7 yards
height
1/36 = x/6
x= 1/6 yards
the total volume of dirt needed is length x width x height.
4*7*(1/6) = 28/6 yards or 4 2/3 yards
since the store sells in increments of 1/4 yards, round 4 2/3 to nearest fourth (3/4) so you need to order 4 3/4 yards of topsoil.
please give thanks :)