Question 243622
5x + 4y = 8
4y=-5x+8
y=-5x/4+8/4
y=-5x/4+2
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4x - 5y = 4
-5y=-4x+4
y=-4x/-5+4/-5
y=4x/5-4/5
slopes are -5/4 & 4/5 therefore these lines are perpendicular.