So basically you have 12 options. Red 1, Red 2, Red 3, Blue 1, Blue 2, Blue 3, Blue 4, White 1, White 2, White 3, White 4, and White 5. Each of these are worth 8.33%. Because there are 3 red balls, you multiply 8.33 by three, which equals 24.99, which is about 25%. So, you have a 25% chance of getting a red ball.