Question

a marble is drawn from a jar containing red, blue, and white marbles. p (red) 0.40 and p (blue) 0.25. what is p (white)

Answer 1

25.35. Here's what you do, if those numbers are multiplied by a 100, they'd be40% red, and 25% blue. So the white is the rest. So you add 25%+40%=100%; 
Answer: 35%. Divide by 100, .35. Boom! you got your answer;)