Help me please ! in going to fail

Last saturday, the museum box office sold 281 tickets for a total of $3,954. adults ticket cost $15, and students ticket cost $12. how many of each kind of tickets were sold?

Simplify the expression. -2/5(10+15m-20n)

Abag contains 3 red marbles, 2 blue marbles, and 2 green marbles. one marble is picked, then another marble. assume that the selections are made with replacement. a) find the probability of picking two red marbles with replacement. b) find the probability of picking a red marble and a blue marble. assume the selections are made without replacement. c) find the probability of picking two red marbles without replacement. d) find the probability of picking a red marble and a blue marble without replacement.