1/2+2/3=7/6

1/3+ 1/4=7/ 12

1/3+3/4= 13/ 12

1/4+ 1/5=9/20

1/4+4/5=2 1/20

...

1/n+ 1/n+ 1 = n+n+ 1/n *(n+ 1)

1/n- 1+n- 1/n = n *(n- 1)+ 1/n *(n- 1)

3/4+ 1/5=4/5 3/4- 1/5= 1 1/20 5/6+2/9= 19/ 18 5/6-2/9= 1 1/ 18 2/3+3/5= 19/ 15

2/3-3/5= 1/ 15 6/7+ 1/2= 19/ 14 6/7- 1/2=5/ 14 2/3+ 1/6=5/6 1/3+ 1/4=7/ 12

1/3- 1/4= 1/ 12 1/5+ 1/7= 12/35 1/5- 1/7=2/35 1/4+ 1/9= 13/36 1/4- 1/9=5/36

1/8+ 1/9= 17/72 1/8- 1/9= 1/72 1/ 10+7/9=79/90 5/7- 1/6=23/42 1-5/9=4/9

1/5+3/8=23/40 3/4+ 1/5= 19/20 2/3-3/5= 1/5 1-2/5=3/5 5/8- 1/9=37/72

1/ 10- 1/20= 1/20 1/6+3/8= 13/24 5/9- 1/2= 1/ 18 2/3+ 1/4= 1 1/ 12 1/2+ 1/3=5/6

5/6+ 1/ 18=8/9 3/5- 1/3=4/ 15 17/ 15- 1/3=4/5 1 1/ 12-2/3= 1/4 1/2- 1/4= 1/4

1/7- 1/8= 1/56 1/3- 1/9=2/9 5/6- 1/2= 1/3 1-2/3= 1/3 5/8- 1/6= 1 1/24

1/3+ 1/6= 1/2 3/4- 1/2= 1/4 1/5+ 1/8= 13/40 5/6+4/9=23/ 18 5/9-2/5=7/45

3/7+5/2=4 1/ 14 5/8+9/ 10=6 1/40 1 1/ 12-8/ 15=23/60 1/4+ 1/6=5/ 12 1/4- 1/6= 1/ 12

1-6/7= 1/7 1 1/ 12-2/3= 1/4 3/ 10+2/5=7/ 10 7/8- 1/4=5/8 3/4+5/ 12=7/6

3/5-3/7=6/35 5/4-5/ 12=5/6 1/5- 1/9=4/45 1/3- 1/8=5/24 1 1/6-2/9=29/ 18

1/5+ 1/9= 14/45 1-2/5=3/5 7/4+ 1/7=53/28 1- 1/9=8/9 2/3-2/7=8/2 1

5/6+ 1/2=4/3 4/3-3/4=7/ 12 1-4/7=3/7 4/3+3/2= 17/6 5/9+ 18/5=5/6

3/8+7/ 10+5/8= 17/ 10 7/8-( 1/8+3/4)=0 4/7+ 1/6-4/7= 1/6

2-7/9-2/9= 1 3/5+7/8+2/5= 15/8 7/9-( 1/9+ 1/3)= 1/3

1/4+(2/5+3/4)=7/5 5/6-3/ 10+ 1/6-7/ 10=0 3/4+ 1/6-2/3= 1/4

7/8- 1/4+4/9=77/72 1- 1/3+2/7=20/2 1 1/2+4/5-3/ 10= 1

5/6-(2/3- 1/9)=5/ 18 9/ 10-(3/4+ 1/8)= 1/40 1/2+2/3-3/4=5/ 12

7/8- 1/6+ 1/4=23/24 1-(3/4-2/9)= 17/36 9/ 10- 1/5- 1/2= 1/5

1/4+3/7+ 1/2=33/28 7/8-(2/3+ 1/6)= 1/24 1-( 1/3+3/5)= 1/ 15

1/2+ 1/4+ 1/3= 13/ 12 7/8+ 1/4+ 1/2=5/8 5/7-(4/7+ 1/9)=2/63

1- 1/4- 1/2= 1/4 3/4- 1/6- 1/3= 1/4 3/ 10+ 1/4+2/5= 19/20

2/3+ 1/6+ 1/ 12= 1 1/ 12 1- 1/4-2/5=7/20 1/2+ 1/9+ 1/ 12=25/36

1/7+3/8+5/7= 1/7+5/7+3/8=6/7+3/8=48/56+2 1/56=69/56

The denominator remains the same first, and then the number is subtracted.

1-5/9-4/9= 1-(5/9+4/9)= 1- 1=0

Subtracting several numbers in a row is equivalent to subtracting these numbers and adding them up.

4/ 1 1+5/6-4/ 1 1=4/ 1 1-4/ 1 1+5/6=0+5/6=5/6

Operate the same denominator first.

3/4- 1/6+ 1/4=3/4+ 1/4- 1/6= 1- 1/6=5/6

The symbol follows the last number and moves with the symbol.

7/8-( 1/5+ 1/3)=7/8-(3/ 15+5/ 15)=7/8-8/ 15=4 1/ 120

There is no skill in this, only points.

1+(1/3-1/6) =1+(2/6-1/6) =1+1again.

Don't forget that molecules have to be multiplied when they are divided.

( 1)7/ 12+2/ 12=9/ 12=3/4

(2) 1/3+3/8=8/24+9/24= 17/24

(3)2/3-2/5= 10/ 15-6/ 15=4/ 15

(4)5/8+2/7=35/56+ 16/56=5 1/56

1) 4/ 14+8/ 14=6/7

2) 7/ 10+2/ 10=9/ 10

3) 4/7-3/7= 1/7

4) 3/ 14+7/ 14=5/7

5) 4/ 1 1+5/ 1 1=9/ 1 1

6) 4/ 15+2/ 15=2/5

7) 9/ 10-3/ 10=6/ 10

8) 7/ 13+5/ 13= 12/ 13

9) 6/ 13+5/ 13= 1 1/ 13

10) 2/8+3/8=5/8

1 1) 9/ 13-9/ 13=0

12) 9/ 13+3/ 13= 12/ 13

13) 1 1/ 12-4/ 12=7/ 12

14) 14/ 15-3/ 15= 1 1/ 15

15) 1/ 13+ 1 1/ 13= 12/ 13

16) 2/ 15-2/ 15=0

17) 7/ 12+3/ 12=5/6

18) 12/ 15-9/ 15= 1/5

19) 1/8+2/8=3/8

20) 6/7-6/7= 0

2 1) 10/ 13+2/ 13= 12/ 13

22) 2/ 13+7/ 13=9/ 13

23) 1/ 1 1+8/ 1 1=9/ 1 1

24) 3/4- 1/4= 1/2

25) 4/ 15+ 10/ 15= 14/ 15

26) 12/ 14-4/ 14=4/7

27) 7/ 13+2/ 13=9/ 13

28) 8/ 13- 1/ 13=7/ 13

29) 12/ 14- 12/ 14=0

30) 12/ 13-6/ 13=6/ 13