Human: Johnny buys 15 packs of colored pencils for his class. Each pack has a red, yellow, and green pencil inside. When he gets home he notices that 3 of the packs have two extra red pencils inside. How many red colored pencils did Johnny buy? Assistant: 
How many red pencils did Johnny buy? ** Johnny bought 15 packs, and every normal pack has 1 red pencil. He should have 15 * 1 = <<15*1=15>>15 red pencils.
How many extra red pencils are in the packs? ** 3 of the packs have 2 extra red colored pencils, so there are 3 * 2 = <<3*2=6>>6 extra red pencils.
How many red colored pencils did Johnny buy? ** In total, Johnny has 15 + 6 = <<15+6=21>>21 red colored pencils.
#### 21