Jackie has a pack of twelve pens with 3 blue, 4 red, 3 green and 2 black. What is the probability that she picks a red pen, does not replace it, picks a blue pen, does not replace it and then picks another red pen?

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!

c

step-by-step explanation: