To add 13/18 and 7/12, first find a common denominator:

18 = 233
12 = 223

The least common multiple is 223*3 = 36. Now rewrite both fractions with this denominator:

13/18 = 26/36
7/12 = 21/36

Now add both fractions:

26/36 + 21/36 = 47/36

Next, subtract 3/5 from 5/7:

To subtract 3/5 from 5/7, find a common denominator:

5 = 5
7 = 7

The least common multiple is 5*7 = 35. Now rewrite both fractions with this denominator:

5/7 = 25/35
3/5 = 21/35

Now subtract the fractions:

25/35 - 21/35 = 4/35

Finally, subtract 3/8 from 5/6 and then subtract 1/12 from the result:

To subtract 3/8 from 5/6, find a common denominator:

8 = 8
6 = 2*3

The least common multiple is 8*3 = 24. Now rewrite both fractions with this denominator:

5/6 = 20/24
3/8 = 9/24

Now subtract the fractions:

20/24 - 9/24 = 11/24

Next, subtract 1/12 from the result:

To subtract 1/12 from 11/24, find a common denominator:

12 = 223
24 = 222*3

The least common multiple is 222*3 = 24. Now rewrite both fractions with this denominator:

11/24 = 11/24
1/12 = 2/24

Now subtract the fractions:

11/24 - 2/24 = 9/24

Therefore:
13/18 + 7/12 = 47/36
5/7 - 3/5 = 4/35
5/6 - 3/8 - 1/12 = 9/24