Mixing it up
I start with two full mugs, one containing milk and the other containing tea, in exactly equal amounts. I transfer 3 spoonsful of milk from the first mug to the second, and stir thoroughly. Then I transfer 3 spoonsful from the now-milky tea in the second mug back into the first mug.
Which is greater: the amount of tea now in the first mug or the amount of milk now in the second mug?