№1
1)1 1/2-3/5=3/2-3/5=15/10-6/10=9/10
2)2 2/3:6/1=8/3*1/6=4/9
3)4/9*9/10=4/10=0,4
4)3-0,4=2,6
№2
4 - 2 1/4 * (1 1/3 - 5/6) : 10 = 3 71/80
1) 1 1/3 - 5/6 = 1 2/6 - 5/6 = 8/6 - 5/6 = 3/62) 2 1/4 * 3/6 = 9/4 * 3/6 = 27/24 = 9/83) 9/8 : 10 = 9/8 * 1/10 = 9/804) 4 - 9/80 = 3 80/80 - 9/80 = 3 71/80