Answer:

Explanation:
So there is 40marbles in total
The probability of picking a red marble first is 
 because there is 10 red marbles out of 40 total marbles
 because there is 10 red marbles out of 40 total marbles
Then you replace it and I'm going to assume that you put the red marble back.
Then you would still have 40 marbles and the probability of picking a blue one is 
 because there is 18 blue marbles.
 because there is 18 blue marbles.
 Then you multiply 
 and
 and 
 and that is
 and that is 

Hope this helps and If I'm wrong pls tell me.