Explanation:
maybe this is not the full expression, as you wrote the line equation in a funny way.
I understand the following :
the line is
y = (-2/5)×x - 7
perpendicular means crossing at a right angle (90 degrees).
the slope of the original line is -2/5.
as in every line equation, the slope is the factor of x. and it expresses the ratio y/x indicating the amount of units y is changing, when x changes a certain amount of units (e.g. when going from one point on the line to another).
the perpendicular slope turns the original y/x ratio upside-down, and also flips the sign.
so, it is 5/2.
the equation for the perpendicular line looks like
y = (5/2)×x + b
now what is b ?
for this we use the specified point on the line : (4, -1)
and we put these values as x and y into the equation :
-1 = (5/2)×4 + b = 5×2 + b = 10 + b
b = -11
and so, the full equation of the perpendicular line is
y = (5/2)×x - 11