To construct the missing parts of the two-way table, we simply need to subtract the existing values from the totals provided.
For 8th graders who can swim, we subtract 15 from the total of 65, which gives us 50.
For 7th graders who cannot swim, we subtract 25 from the total of 65, which gives us 40.
Therefore, the completed two-way table would be as follows:
Can Swim Cannot Swim Totals
7th Graders 15 40 55
8th Graders 50 25 75
Totals 65 65 130