You can
put this solution on YOUR website!I am assuming that no one is running for two or three different positions at the same time.
The choices for the three positions are independent.
There are 3 ways to chose the President.
For each one of those choices, you still have four different ways to choose a Vice President.
That gives you

ways to chose President plus Vice President.
For each of those 12 choices, you still have 7 ways to choose a secretary,
so there are

ways to chose the set of 3 class officers.