I mean this very kindly. You WRONGLY seem to think that “doing” math means doing arithmetic on a pre-defined formula. That is mechanics that computers can, and do, do. Doing math is a human process involving creative thought. Sometimes that creative thought is as simple as identifying which formula applies, but most of the time it involves creating such a formula on your own. Teachers who treat math as a set of formulas to memorize are horrible teachers.
We ask in our guidelines that you give us some indication of what topic in math you are currently studying. You posted this problem in probability and statistics. It has nothing to do with that branch of mathematics. What are you currently studying in math class?