1) (4,5: 3/5+3,75)*2/9-2/3= 2) 5/8+1 1/2*(17/4: 17)+3,75: 5/6= 3) (1/2+0,125-1/6)*(6,4: 80/3)+1/8=

№1
1) 4,5 : 3/5 = 4,5 : 0,6 = 7,5 
2) 7,5 + 3,75 = 11,25 = 11  25/100 = 11  1/4
3)  11  1/4 * 2/9 = 45/4 * 2/9 = 5/2
4) 5/2 - 2/3 = 15/6 - 4/6 = 11/6 = 1  5/6

№2
1) 17/4 : 17 = 1/4
2) 1 1/2 * 5/4 = 3/2 * 5/4 = 15/8
3) 3,75 : 5/6 = 3  3/4 : 5/6 = 15/4 : 5/6 = 9/2
4) 5/8 + 15/8 = 20/8
5) 20/8 + 9/2 = 20/8 + 36/8 = 56/8 = 7

№3
1) 1/2 + 0,125 = 1/2 + 1/8 = 4/8 + 1/8 = 5/8
2) 5/8 - 1/6 = 15/24 - 4/24 = 11/24
3) 6,4 : 80/3 = 64/10 : 80/3 = 24/100
4) 11/24 * 24/100 = 11/100 = 0,11
5)  0,11 + 1/8 = 0,11 + 0,125 = 0,235