Bike is rented for $9/hour and scooter can be rented for $10/hour. So for the bike it would be 9b (9xb) and the scooter is 10s (10xs) for the total cost of both of them the answer is 9b+10s
if events X and Y are independent, then for intersection we multiply the probability
P(Y∩X) = P(Y) * P(X)
We know that

Now we replace P(Y) * P(X) for P(Y∩X)

Cancel out P(X)
So 
Like that

Now we replace P(X) * P(Y) for P(X∩Y)

Cancel out P(Y)
So 
P(Y | X) = P(Y) and P(X | Y) = P(X) are true
maybe 8:02 maybe not surew