During a Mathematics class, the teacher asks, "Class, who knows what 2 + 2 is?" Realizing how simple the question, Johnny raises his hand, but the teacher pointed to another student because Johnny always know how to behave silly in class. Johnny was upset.
The teacher asks again, "Who knows what 5 + 5 is?" Johnny raises his hand again, but the teacher still didn't point at him.
The teacher asks his third question, "What's X if 40X + 30 = 120X?" Everybody raises their hands again but the teacher decided to pick Johnny. Johnny replies, "But sir, I did not raise up my hand."