Suppose that n raisins have been carefully mixed with a batch of dough. If we bake k (k > 4) raisin buns of equal size from its mixture, what is the probability that one out of four randomly selected buns contains no raisins

Carli has 90 apps on her phone. braylen has half the amount of apps as theiss. if carli has three timesthe amount of apps as theiss,how many apps does braylen have? let b represent the number of braylen's apps and t represent the number of theiss's apps.