Looks like you want to set up a table with up to 4 rows and 4 columns.
Column 1 would have your descriptions of each row.
Row 1 would have the descriptions of each column
Column 4 would have the totals of the rows, and Row 4 would have the totals of the columns.
Aesthetically, I would put Freshmen in row 2 and Sophomores in row 3, but that doesn't actually matter.
(BLANK) | IN FAVOR | OPPOSED | TOTAL
9th grade...|......68.......|.......20.......| 88
10th grade.|.......34......|.......60........| 94
Total.........|......102......|.......80.......| 182
That helps us to find the total number of people polled, 182.
Once you have your table set up, you'll divide the number of each cell by the total. This will give you the decimal form of a percent. And now it's relative frequency table. Different teachers have you round to different places, so hopefully you know where your teacher wants you to round to.
(BLANK) | IN FAVOR | OPPOSED | TOTAL
9th grade...| 0.3736...| 0.1099........| 0.4835
10th grade.| 0.1868...| 0.3297........| 0.5165
Total.........| 0.5604...| 0.4396........| 1
