Hello Tubiao!
You can determine the amount by figuring out the cubic footage. First you have to multiply the length (14 feet) by the width (10 feet) times the depth (4 inches or .33 feet). 14 x 10 x .33 = 46.2 cubic feet. Now you have to divided it by 27 equals 1.7 cubic yards. This means that you require 1.7 cubic yards of concrete.
You can determine the amount by figuring out the cubic footage. First you have to multiply the length (14 feet) by the width (10 feet) times the depth (4 inches or .33 feet). 14 x 10 x .33 = 46.2 cubic feet. Now you have to divided it by 27 equals 1.7 cubic yards. This means that you require 1.7 cubic yards of concrete.