I'm not sure how to do the problem geometrically, but if you move r red marbles and b blue marbles, there will be:
250-r red marbles and 200-b blue marbles in Container A
600+r red marbles and 150+b blue marbles in Container B
So we need 25% of the marbles in Container A to be red:
250-r = 0.25 * (250-r + 200-b)
And 75% of the marbles in Container B to be red:
600+r = 0.75 * (600+r + 150+b)
From here, you solve the two equations in the two unknowns r and b.