can someone explain this to me please? giving brainlest to the person who explains it and gives the right answer

Abag contains 3 red marbles 4 white marbles and 5 blue marbles if one marble is drawn from the bag what is the probability that the marble will be blue

What is the size of the matrix resulting from

When 142 is added to a number the result is 64 more then 3 times the number. option 35 37 39 41