The average weight of 6 boys gets increased by 5kg if a boy with a weight of 20kg is replaced by a new boy. What is the weight of the new boy?

 Let's denote the average weight of the initial 6 boys as

$�$, and let $�$ be the weight of the boy who is replaced (20 kg). The average weight increases by 5 kg when the new boy is introduced.

The total weight of the initial 6 boys is $6�$. When the new boy replaces the boy with a weight of 20 kg, the total weight becomes $6�-�+\text{weight of the new boy}$.

The increase in total weight is given as 5 kg:

$(6�-�+\text{weight of the new boy})-6�=5$

Now, substitute the value of $�$ (20 kg) into the equation:

$(6�-20+\text{weight of the new boy})-6�=5$

Combine like terms:

$-20+\text{weight of the new boy}=5$

Add 20 to both sides:

$\text{weight of the new boy}=25$

So, the weight of the new boy is 25 kg.