Решить пример, (7 целых 1/2 умножить на 2 целых 2/3 -12 целых 1/4 : 7/9) : 6+10 целых 2/21 (6 класс)

(7 1/2 * 2 2/3 - 12 1/4 : 7/9) : 6 + 10 2/21 = 10 целых 45/56

1) 7 1/2 * 2 2/3 = 15/2 * 8/3 = (5*4)/(1*1) = 20
2) 12 1/4 : 7/9 = 49/4 * 9/7 = (7*9)/(4*1) = 63/4 = 15 3/4
3) 20 - 15 3/4 = 19 4/4 - 15 3/4 = 4 1/4 = 17/4
4) 17/4 : 6 = 17/4 * 1/6 = 17/24 
5) 17/24 + 10 2/21 = 119/168 + 10 16/168 = 10 135/168 = 10 45/56

(7 1/2*2 2/3-12 1/4 + 7/9):6+10 2/21= (15/2*8/3-49/4*9/7)*1/6+212/21=(5*4-7/9*9)*1/6+212/21=(20-63/4)*1/6+212/21=17/4*1/6+212/21=17/24+212/21=605/56