Alguien que me ayude con estos ejercicios :( son para hoy máx 15 pm Plsss :(

How many different ways can you make change for $.50 using only nickels,dimes, and quarters?

The number if marbles of different colors stored in a hat is listed below: 4 red marbles 10 green marbles 7 blue marbles. without looking in the hat, dan takes out a marble at random. he replaces the marble and then takes out another marble from the hat. what is the probability that dan takes out a blue marble in both draws?

Which inequality is equivalent to -3x < -12? x < 4 , x < -4 , x > 4, x > -4