5 in 12-7 in18 = 5/12-7/18 = (15-14)/36 =1/.

20% 13+4% 1 = 13/20+ 1/4 = (3+5)/20 = 8/20 = 2/5

3/4- 12-5+2/3 = 3/4-5/ 12/3 = (9-5+8)/ 12 = 12/ 12 = 65438+

3+of 8 (7 of 5- 12 of 6) = 3/8+(5/6-7/12) = 3/8+(10/17/.

15 7-3 1+5 1 = 7/ 15- 1/3+ 1/5 = (7-5+3)/ 15 = 5

28 o'clock 15-(7 o'clock 2+ 14 o'clock 5) =15/28-(2/7+5/14) =15/28-(4//kloc)

2:

( 1)x- 12 5 = 3/8+5/ 12 = 9/24+ 10/24 = 19/24。 X = 65438+。

(2)x+ 18 7 = 5/9-7/ 18 =( 10-7)/ 18 = 3/ 18 = 1/6。

(3) 2/3-X = 3/5，X = 2/3-3/5 =( 10-9)/ 15 = 1/ 15。 X = 1/65438+。

3:

1, with four ribbons of red, yellow, blue and green. The red one is 2/5 meters longer than the yellow one, the blue one is 1 meter longer than the green one and 3/4 meters shorter than the red one. Students, which color ribbon is the longest? Which color ribbon is the shortest? How many meters is the difference between them?

Red and yellow = 2/5 meters

Blue-green = 65438+ 1 over 00.

Red and blue = 3/4

Solution: Yellow = red -2/5=3/4+ blue -2/5= blue +7/20 Yellow-blue =7/20.

Red =3/4+ Blue Red-Blue =3/4= 15/20

Green = blue-110 green-blue =-110

∫15/20 > 7/20 >-110, ∴ red >; Yellow > blue > green.