Cracking my head up with Geometry!

I was here at the library for almost an hour trying to solve a very perplexed geometrical equation that my geometry teacher gave me. It says that

if the angle from pt. 1 which is pt1. (-4,5) and pt.2 (x,9) to the line through
pt.3(-2,4)and Pt.4(9,1) is 135 degrees. Find the value of X.

I know this was a pretty basic mathematical equation at the first glance since it only requires to look for a certain point on the cartesian plane, but I must admit it. It cracked me up. I could say that i am not that poor in mathematics, as a matter of fact I got the highest scores on major exams on my Analytical geometry and differential calculus respectively on Preliminaries and Midterms.

I just did all I could. I try to derived the equation to solve for the slope which is M=(y2-y1)/x2-x1... and come up to the derived equation which is x2=(y2-y1/m)+x1. But no matter how I tried to test and proved the derived equation. it just come up to wrong answer. OK I give up!

But I just love mathematics and numbers so much...eventhough the subject seems to doesnt like me.