Question

Need to find the perpidicular line of 7x +5y = -3

Answer 1

The slope of a line perpendicular to a line of slope m is -1/m. What's the slope of the given line?

Answer 2

First simplify your formula to standard y=mx+b format:
7x+5y=-3
5y=-7x-3
y=(-7/5)x-(3/5)

Now the perpendicular slope is -1/m so:
-1/(-7/5)=5/7

So your answer is y=(5/7)x

If you want it to have the same intercept as your original formula then it would be
y=(5/7)x-3