Given data
The mass of the board is mb = 4 kg
The mass of block A is mA = 30 kg
The mass of the block B is mB = 25 kg
The location distance of block A from the pivot point is d = 25 m
The location distance of block B from the pivot point at the right end is x.
The figure for the above configuration can be drawn as follows:
Taking the moment about the pivot point, the expression is written as follows:
[tex]\begin{gathered} m_A\times d-m_B\times(x)=0 \\ m_A\times d=m_B\times x \\ x=\frac{m_A\times d}{m_B} \end{gathered}[/tex]Substitute the value in the above equation.
[tex]\begin{gathered} x=\frac{30\text{ kg}\times25\text{ m}}{25\text{ kg}} \\ x=30\text{ m} \end{gathered}[/tex]Thus, the distance at which it must be located in the right end from the pivot point is 30 m.