The sum of two rational number is -5/7 . If one of the number is -11/21 , find the number

Thats all no more questions but plz answer quickly only 6 questions plz answer quickly plz PLEASE

Solution-

EQUATION-  -11/21 + x = -5/7

x= -5/7 + 11/21

=   -4/21 


Hence, the other number is -4/21.
 

Let the other number be x .
Then ,
-11/21 + x = -5/7
so transporting x and -5/7 we get
-11/21 + 5/7 = x
- 11/21 + 15/21 = x
4/21 = x


so the answer is 4/21

hey man what's wrong with the answer

Thanks for the answer