I find the linear interpolation rule used in the schweser material different than the normal linear interpolation rule I use, can anyone explain for me the difference?

Liner Interpolation equation used in the CFA material=Interpolated rate = rate for lower bound + (# of years for interpolated rate – # of years for lower bound)(higher bound rate – lower bound rate)/(# of years for upper bound – # of years for lower bound)

the normal Lineral Interpolation equation=(# of years for upper bound-# of years for interpolated rate )*rate of lower bound+(# of years for interpolated rate-# of years for lower bound)* rate of upper bound/# of years for lower bound