Your lack of a question or problem description leaves one to assume you're trying to calculate an average and not coming up with the correct answer.
You've got this in your code:
int total = M1+M2+M3;
System.out.println("Average of three numbers is: " +
total / 60)*100) ;
So how do you calculate an average? You add up the values you have, in your case 15, 20, and 10, then divide that total by the number of values you added together, 3.
Where did you get the "divided by 60, times 100" garbage from?