You will notice that 48°, x, and x lie upon a straight line. The sum of those angles must then be equal to 180°. Which means:
48+x+x=180
48+2x=180
2x=132
x=66°
Answer:
To be precise, I think it's a pattern question, where you have to add 4 to each number. I'm not very sure though.
5x - 20 = 8x - 65
-20 = 3x - 65
3x = 45
x = 15