Answer: 126.
Here is an example of my work, just add your prefered numbers and boom, 126.
Also, mine was 200 instead of 300 and I got 84. So just plug in your number and boom.
5x - 20 = 8x - 65
-20 = 3x - 65
3x = 45
x = 15
hmmmm i think there is another part of this