Let the share of each girl be \( x \). According to the problem, each boy receives \( x + 20 \).
Since there are 5 boys and 4 girls, we can express the total amount shared among them as follows:
\[ \text{Total amount} = \text{Amount received by boys} + \text{Amount received by girls} \]
The amount received by the boys can be represented as:
\[ 5(x + 20) \]
And the amount received by the girls is:
\[ 4x \]
Putting it all together, the total amount shared can be written as:
\[ 5(x + 20) + 4x = 18100 \]
Now, let's simplify the equation:
\[ 5x + 100 + 4x = 18100 \]
Combining like terms gives us:
\[ 9x + 100 = 18100 \]
Next, subtract 100 from both sides:
\[ 9x = 18100 - 100 \]
\[ 9x = 18000 \]
Now, divide by 9 to find \( x \):
\[ x = \frac{18000}{9} = 2000 \]
So, the share of each girl is \( N2000 \). Consequently, the share of each boy, which is \( x + 20 \), is:
\[ \text{Boy's share} = 2000 + 20 = 2020 \]
Thus, the boy's share is:
\[ \boxed{2020} \]