I'm only doing the first part of the question, because i can't figure out the faster way of doing the the second part.

Let W = White, R = Red

First Can:

(4/4)W

(3/4)W

(3/4)W + (1/4)[(1/4)W + (3/4)R]

=(13/16)W + (3/16)R

Second Can:

(3/4)R

(1/4)W + (3/4)R

(3/4)[(1/4)W + (3/4)R]

=(3/16)W + (9/16)R

Therefore the first can has 81.25% White and 18.75% Red. The second can has 25% White and 75% Red.

I think i did it right, and hopefully it helped u. =)