Answer:

Step-by-step explanation:
Given: 
To find: 
Solution:
A relation is said to be a function if each and every element of the domain has a unique image in the co-domain.
Inverse of a function exist if it is both one to one and onto.


For the domain
3-x >= 0
3 >= x
I think the answer is 9-25x
Answer:
54 kg
Step-by-step explanation:
Total weight of 7 boys is 392 kg. And other 6 boys total weight is 338 kg.
So the 7th boy's weight is (392-338)=54 kg
Solution is in the picture