1)2 3/20 + 1 5/12 = 43/20 +
17/12 = (43 × 3 + 17 × 5)/60 =(129/60 + 85/60
= 214/60 = 107/30 = 3 17/30
2)3 17/30 ÷ 27 13/15 = 107/30 ÷
418/15 = 107/30 × 15/418 =
107/836
3)1,75*2/3=1 75/100
× 2/3 = 7/4 × 2/3
= 7/6 = 1 1/6
4)1,75*1 1/8 = 1 75/100
× 1 1/8 = 7/4 × 9/8
= 63/32 = 1 31/32
5) 1 1/6 - 1 31/32 = 7/6
- 63/32 = (7 × 16 - 63 ×
3)/96 = (112 - 189)/96 =
- 77/96
6) - 77/96 ÷ 7/12 = - 77/96 × 12/7
= - 11/8 = - 1 3/8
7) 107/836 ÷ (- 1 3/8) = 107/836 ÷ ( -
11/8) = 107/836 × ( - 8/11) =
- 214/2299
Ответ - 214/2299