L1 is parallel L2 and L3 is perpendicular to L2. If m3=-2/3, find m1

How am I supposed to answer this and what formula should I use? I'm really studying hard right now yet my teacher is quiet off and I cant find the right words to search it on internet.

2 answers

perpendicular lines with slopes m1 and m3 obey

m1 * m3 = -1

did you try googling slopes of perpendicular lines?
If not, you didn't try very hard.
I sould try harder, by the way thank you very much!