need explantion for A,B,C

The following data represent salaries, in thousands of dollars, for employees of a small company. Notice the data have been sorted in increasing order. 54 , 55, 55, 57, 57, 59, 60, 65, 65, 65, 66, 68, 68, 69, 69, 70, 70, 70, 75, 75, 75, 75, 77, 82, 82, 82, 88, 89, 89, 91, 91, 97, 98, 98, 98 If you create a frequency table with five classes: a) What is the class width (give as a whole number)? b) If the lower limit of the first class is 54, what is the upper limit of the first class (using the above class width for the frequency table)? c) What is the relative frequency of the first class (using above class width and class limits)