Explain relative velocity of man with respect to rain?

Concept.
For rain problem
If ##vecV_A and vecV_B## are velocities of objects ##A and B## respectively then
##vecV_(AB)=vecV_A-vecV_B## is the velocity of ##A## with respect to ##B##.
Following the above logic
##vecV_(rm)=vecV_r -vecV_m## is velocity of rain with respect to man.

See the vector representation on the right side of the figure above.
Similar steps need to be followed if ##vecV_(mr)## velocity of man with respect to rain is to be found.