Math Qn on Red and Blue Marbles

This is posted by LL ☺
Someone posted the following question on the cbox:

Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles.How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red?

LL's solution:

before............after
A red 250.........1 unit(u)
..blue 200........3 units(u)

B red 600.........3 parts(p)
..blue 150........1 part(p)

4u+4p=1200 (total of red and blue marbles in containers A and B)
->1u+1p=300
3p+u=850 (total red marbles)
(3p+u)-(1u+1p)=850-300
2p=550, p=275
At first, container B has 150 blue balls.
Now, container B has 1 part=275 which is increased by 275-150=125 blue marbles
At first, container B has 600 red balls.
Now, container B has 3 parts=275x3=825 which is increased by 825-600=225 red marbles

Therefore, 225 red and 125 blue marbles must be moved from Container A to Container B.