(4.1- 2 3/4):(1 16/21 + 4 2/3)
помогите!

(4,1 - 2 3/4) : (1 16/21 + 4 2/3) = 0,21 
1) 4,1 - 2 3/4 = 41/10 - 11/4 = 82/20 - 55/20 = 27/20 =1 7/20
2) 1 16/21 + 4 2/3 = 1 16/21 + 4 14/21 = 5 30/21 = 6 9/21 = 6 3/7
3) 1 7/20 : 6 3/7 = 27/20 : 45/7 = 27/20 * 7/45 = 189/900 = 21/100 = 0,21