Rate of change of y respect to x as y=4-5/8x

Given a funtion in slope-intercept form:
y=mx+b
m=slope or rate of change.
b=y-intercept.

In tyis funtion:
y=4-5/8 x
y=-5/8 x+4

m=is the number beside "x"=-5/8

Therefore:
the rate of change of y respect to x will be -5/8.

That is so true, i can’t believe how true this is