Please answer correctly

Isee the amount was $90.00 then reduced to $75.00 , what is the percent ?

What signals you that factoring by grouping is the best method to use when factoring a problem?

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.