calculations?

1        1       4

---  +  --- =  ---

3        9        9

You have to make sure the denominator match. You can easily make 3 into 9 by multiplying it by 3, but what you do to the bottom you have to do the top.

1*3        1       4

---  +  --- =  ---

3*3        9        9

Then your equation would be:

3        1       4

---  +  --- =  ---

9        9        9

The by solving that you get 4/9.

1/3 + 1/9 = 4/9

but what's the calculation

Same with 1/2 - 2/5 = 1/10 

calculations please

Simplify the following:
1/3+1/9

Put 1/3+1/9 over the common denominator 9. 1/3+1/9  =  3/9+1/9:
3/9+1/9

3/9+1/9  =  (3+1)/9:
(3+1)/9

3+1 = 4:
Answer: |  4/9

Simplify the following:
1/2-2/5

Put 1/2-2/5 over the common denominator 10. 1/2-2/5  =  5/10+(2 (-2))/10:
5/10+(2 (-2))/10

2 (-2)  =  -4:
5/10+-4/10

5/10-(4)/10  =  (5-4)/10:
(5-4)/10

5-4 = 1:
Answer: |  1/10

Is this kindergarten maths or something. Probably about the reach of the members scope anyway