The lines below are perpendicular. If the slope of the green line is 3/2, what is the slope of the red line?

I’m stuck on this equation, anyone got the answer?

Scenario: a rectangular plot of ground is 5 meters longer than it is wide. its area is 20,000 square meters. question: what equation will you find the dimensions? note: let w represent the width. options: w(w+5)=20,000 w^2=20,000+5 (w(w+5))/2=20,000 w+2(w+5)=20,000

Can someone show me step by step how to do this?