If harriet rolls the number cube 39 times, how many times can you expect to roll a 3 or 4

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236

Cody ran nine miles on his first day of training. the next day he ran 1/8 that distance. how far did he run the second day?