Given:
PO is the perpendicular bisector of triangle MON.
![\begin{gathered} MP=2x+5 \\ \angle OPN=5x+10 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/fao5yy83hyx0ywzb2u2yshzm7m8izi8p14.png)
1. To find the value of x:
Since,
![OP\perp MN](https://img.qammunity.org/2023/formulas/mathematics/college/d9nglk7wjimz1jgav51hwua40wdb6ckagk.png)
Therefore, the angle measure of OPN is 90 degrees.
So that,
![\begin{gathered} \angle OPN=90^(\circ) \\ 5x+10=90 \\ 5x=80 \\ x=16 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/dz1ndrq87s8go88h6xqhcno1dj09z2wzki.png)
Hence the value of x is 16.
2. To find MN:
Since PO is the perpendicular bisector to the side MN.
So, MP=PN
Therefore,
![\begin{gathered} MN=MP+PN \\ =MP+MP \\ =2MP \\ =2(2x+5) \\ =4x+10 \\ =4(16)+10\text{ \lbrack{}Substituting x = 16\rbrack} \\ =64+10 \\ MN=74 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/yl20p8m878pfchnu8u8jo4st50vauz6nu7.png)
Hence, the length of MN is 74.