do you have to say it while flipping your finger up and down over your lips?

Zaphod Beeblebrox?

I’m not a mathematician but if I recall correctly slope is defined the change in y over the change in x. In your formula solved for x, m would represent the inversion of that, the change in x over the change in y.

yup, slope intercept is the name of the formula. m is the slope of the line and b is still the y intercept.