Degrees and identifying the correct amount of triangles (picture provided)

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab

Find an bif a = {3, 6, 9, 12) and b = {2, 4, 6, 8, 10).

The computer that controls a bank's automatic teller machine crashes a mean of 0.6 times per day. what is the probability that, in any seven-day week, the computer will crash less than 5 times? round your answer to four decimal places