3.7/12*(5/12+3/8):1.1/3-1.3/8:(1.1/5-1/4)= помогите решить

Должно получиться 21/38

такой ответ не получается

3 7/12 * (5/12 + 3/8) : 1 1/3 - 1 3/8 : (1 1/5 - 1/4) = 4963/72961) 5/12 + 3/8 = 10/24 + 9/24 = 19/242) 3 7/12 * 19/24 = 43/12 * 19/24 = 817/288 3) 817/288 : 1 1/3 = 817/288 : 4/3 = 817/288 * 3/4 = (817*1)/(96*4) = 817/384 = 2 целых 49/3844) 1 1/5 - 1/4 = 1 4/20 - 5/20 = 24/20 - 5/20 = 19/205) 1 3/8 : 19/20 = 11/8 * 20/19 = (11*5)/(2*19) = 55/38 = 1 целая 17/386) 2 49/384 - 1 17/38 = 2 931/7296 - 1 3264/7296 = 1 8227/7296 - 1 3264/7296 = 4963/7296