Jerseys will sell for $30. Random variable X is number of jerseys that will be sold. E(X)=100 and R is the total revenue (R=30X). What is the expected revenue.

I have no idea what formula to use. I thought conditional probability because revenue is dependent on the sale of the jerseys, but the formula does not match my data, or I am writing it back the front.

Why is it not $3000...?

I think if I knew the formula I could work it out~ maybe :-)