There is such a problem in primary school, which is really out of line. The concept of probability, from high school, is too early now. 1. 1 think of it this way. Divide the 30 balls into 5 parts, each with 6 balls, and take out two red balls, namely 12 red ball and 18 yellow ball.

Similarly, 1.2, 25% is 1/4, divided into four parts, each part has six yellow balls, and the others are red balls.

1.3 The green ball accounts for 1/3, that is, the red ball and the yellow ball * * * account for 2/3, that is, * * *, and there are 24 copies, each of which is 12. That means you need to put 12 green balls.

The other is the question of probability. Try to understand for yourself.