What do you add to 4 7/8 to make 7? what do you add to 2 1/7 to make 4? what do you add to 5 2/9 to make 7? answer these question and explain.

For the first question
The number given is = 4 7/8
                                  = 39/8
Let us assume the number to be added is = x
39/8 + x = 7
(39 + 8x) = 7 * 8
39 + 8x = 56
8x = 56 - 39
8x = 17
x = 17/8
   = 2 1/8
So 2 1/8 should be added to get 7

Regarding the second question
The number given is = 2 1/7
                                 = 15/2
Let us assume the number to be added = y
(15/2) + y = 4
15 + 2y = 4 * 2
15 + 2y = 8
2y = 8 - 15
2y = - 7
y = - 7/2
   = - 3 1/2
So the number that needs to be added is - 3 1/2.

Regarding the third question
The number given is = 5 2/9
                                  = 47/9
Let us assume the number to be added = z
Then
(47/9) + z = 7
47 + 9z = 7 * 9
47 + 9z = 63
9z = 63 - 47
9z = 16
z = 16/9
  = 1 7/9
So the number that needs to be added is 1 7/9.