Question

If 15% of college students own a television and 10% of college students own a stereo and 2% of college students own both television and stereo then the percentage of college students that own either a television or stereo

Answer 1

We know that
15% of college students own a television
10% of college students own a stereo 

then

the percentage of college students that own either a television or stereo is
(15%+10%)=25%

the answer is
25%