What is the equation of the line that passes through (10, 4) and is perpendicular to 5x−y=3

Solve equation for y.

5x - y = 3

-y = -5x + 3

y = (-5x + 3)/(-1)

y = 5x - 3

The slope for this equation is 5.

The slope of the equation we want is the negative reciprocal of 5.

Let m = slope of equation we want.

m = -1/5

We are given the point (10,4).

Plug both into the point-slope formula.

y - 4 = (-1/5)(x - 10)

y - 4 = (-1/5)x + 2

y = (-1/5)x + 2 + 4

The equation we want is

y = (-1/5)x + 6

Did you follow?