Astore sold 30 sweatshirts. white ones cost $10.95 and yellow ones cost $13.50. if $356.55 worth of sweatshirts were sold, how many of each were sold

Successful implementation of a new system is based on three independent modules. module 1 works properly with probability 0.96. for modules 2 and 3, these probabilities equal 0.95 and 0.90. compute the probability that at least one of these three modules fails to work properly.