A pizza store owner noticed that a random count (Y) of pizzas ordered by students who reside on campus has distribution shown below

Y 1 Probability 0.15
Y 2 Prob 0.40
Y 3 Prob 0.25
Y 4 Prob 0.20

1. Find expected number of pizza order E[Y]

2. Determine variance of Y

3. Assume the revenue (R) after selling Y pizzas is measured as
R=8 * Y - 10. Evaluate expected revenue after order is completed, that is E[R]

4. For the same variable R=8 * Y - 10, determine its variance
Var [R]

I am very confused on how to start this off can anyone help me