№3.
3 2/9 - 5,2 - 1 5/9 + 0,2 = (- 5,2 + 0,2) - 1 5/9 + 3 2/9 =
= - 5 - 1 5/9 + 3 2/9 = - (6 5/9 - 3 2/9) = -3 3/9 = - 3 1/3
-7,2 - 2 5/6 - 0,3 + 1 1/3 = - (7,2 +0,3) - (2 5/6 - 1 2/6) =
= - 7,5 - 1 3/6 = -7,5 - 1,5= - (7,5 + 1,5) = - 9
- 1 3/16 + 4 17/25 - 5/16 -1 2/25 - 0,5 =
= - (1 3/16 + 5/16) + (4 17/25 - 1 2/25) - 0,5 =
= - 1 1/2 + 4 3/5 - 0,5 =
= - 1,5 + 3,6 -0,5 = 3,6 - 2 = 1,6
3 5/12 - 1,4 - 5 2/3 - 2,6 + 2 1/4 =
= (3 5/12 + 2 1/4 - 5 2/3 ) - (1,4 + 2,6) =
= (3 5/12 + 2 3/12 - 5 8/12 ) - 4 =
= 0 - 4 = - 4
№5.
(2 2/15 +2 7/10) : 1 2/27 - (2 7/10 - 2 2/15) : 2 3/7 =
= (2 4/30 + 2 21/30 ) * (27/29) - ( 2 21/30 - 2 4/30) * (7/17) =
= 4 5/6 * (27/29) - 17/30 * 7/17 =
= 29/6 * (27/29) - 7/30 =
= 27/6 - 7/30 = (135 -7) /30 =
= 128/30 = 64/15 = 4 4/15