Answer: 5/3
=================================================
Step-by-step explanation:
The standard form equation Ax+By = C has the slope m = -A/B.
Flip the fraction to get -B/A and flip the sign to get B/A.
- Original slope = -A/B
- Perpendicular slope = B/A
Multiplying these fractions together gets us -1. Note: A and B must be nonzero.
-----------
In the case of 3x+5y = 4, the slope is -A/B = -3/5
The negative reciprocal is -(-5/3) = 5/3 which is the perpendicular slope
(-3/5)*(5/3) = -1