A card is drawn from an ordinary pack and a gambler bets that it is a spade or an ace. What are the odds against his winning this bet?

A bag contains $7$ red and $8$ black balls. Find the probability of drawing a red ball in its simplest fraction form.

A bag contains $3$ red balls and $5$ black balls. A ball is drawn at random from the bag. What is the probability that the ball drawn is black in simplest fraction form?

A bag contains $5$ red marbles, $8$ white marbles, and $4$ green marbles. What is the probability that if one marble is taken out of the bag at random, it will be white? (Write the final answer in its simplest fraction form)

A bag contains $5$ red marbles, $8$ white marbles, $4$ green marbles. What is the probability that if one marble is taken out of the bag at random, it will be not green? Write the final answer in the simplest fraction form.