There is a race. Participants A and B.
A finishes in 29 minutes
B finishes in 35 minutes
A is 6 minutes faster than B.
B is 6 minutes slower than B.
Is A 17% or 21% faster than B?
Is B 17% or 21% slower than A?
Title says it all, darn percentages :)
Semper ubi sub ubi.