Let Sunil's weight be 'x kg' and Shyam's weight be 'y kg', where x=y.
Now on adding 5kg on both sides gives,
5x and 5y, where 5x=5y because Euclid's Second Axiom states that,
IF EQUALS ARE ADDED TO EQUALS, THE WHOLES ARE EQUAL.
THANK me if you think I'm correct.