Question

I really don't understand on how to solve this

Answer 1

Hey there! :D

These are vertical angles. They have the same measure, so they are equal to each other. 

$6x+25= 2x+105$

Subtract 25 on both sides. 

$6x=2x+80$

Subtract 2x on both sides. 

$4x=80$

Divide both sides by 4. 

$x=20$

I hope this helps, and have a nice day! 
~kaikers