50ft x 40ft x 0.5ft = 1,000 ft³ of soil needed for the project
1000/3= 333.3 bags of soil would be needed, so round up to 334.
334 x $2.25 = $751.50
convert the feet³ to yards³, divide the 1000 ft³ by 27 (27 ft³ in 1 yard³)
1000/27= 37.037(repeating) yd³ I'll round up to 38 yd³
38yd³ x $18 = $684 + $50 delivery fee = $734
So, the bulk soil is less expensive by $17.50