These are supposed to be easy but i don’t get it

2-digit numbers less than 91 which are 1 less than a multiple of 10

30 points and i will give brainliest the club will base its decision about whether to increase the budget for the indoor rock climbing facility on the analysis of its usage. the decision to increase the budget will depend on whether members are using the indoor facility at least two times a week. use the best measure of center for both data sets to determine whether the club should increase the budget. assume there are four weeks in a month. if you think the data is inconclusive, explain why.

What is the frequency of the sinusoidal graph?