3.8*0.8*3*0.11/2.2/5分之2/2.4/0.19
= (3.8/0.19) * (0.8*3/2.4) * (0.11/2.2) / 5分之2
= 20 * 1 * 1/20 / 5分之2
= 1 / 5分之2
= 1 * 2分之5
= 2分之5
= 2.5