Brain Tuner - Math Game

Brain Tuner - Math Game is a mathematical calculation game for brain stimulation, 20 questions will appear one by one with 4 choices for every calculation containing one correct answer, you need to choose correct answer quickly and tap your finger as fast as possible.It has three levels: Classic, Junior and Boss
For every wrong calculation there would be 5 seconds penalty.
Final Score = Time Taken + (5*Wrong Calculation)Score Criteria: Lower is better