How do u do this with answer plz

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

Find the volume of the solid bounded by the plane z=0 and the paraboloid z=1-x^2 –y^2

F. a fair coin is thrown in the air four times. if the coin lands with the head up on the first three tosses, what is the probability that the coin will land with the head up on the fourth toss? a. 0 b. 1/16 c. 1/8 d. 1/2