1.13

2. 8

3. 2

4. 3

**Explanation**:

If assume the unknown number with a variable , following table can be formed.

Minimum value of a+b+c = (2+6+1) = 9 ( when all of a, b and c are minimum possible)

Maximum value of (a+b+c) = (4+8+3) = 15 ( when all of a, b and c are maximum possible)

Similarly Range ( Minimum and Maximum value) of d+e = (9, 25) and g+h = (3, 7)

As sum of all rows and all columns must be multiple of 3 . So on solving we can see a+b+c = 12, d+e = 17 and g+h = 4

Now

Minimum value of a+d = (2+3) = 5 and maximum value of a+d = 4+5 =9

As sum of C1 = 18 + a +d

So a+d should be divisible by 3 . thus a+d can be either 6 or 9.

Similarly b+g can be 7 or 10. And c+h+e can be of the form 3k + 2

On solving we will see only a+d = 9 will satisfy all the conditions

a+d = 9 means a = 4 and d = 5

e = 12. -> c +h = 5. -> b+c =8

if h =3, then c=2, b=6, g=1

Finally, we get

Now all the question can be answered.