Maryam, did you mistype?
If you meant that the light flashes every 7 seconds, then start by multiplying 60 seconds by 2 minutes to get 120 seconds. Then divide that 120 by 7. And we get just over 17. Since we can't have a fraction of a flash, your answer should be 17 flashes.
If your teacher wants the mixed number, instead of the whole number, then it's 17 and one-seventh flashes.
Let me know if that explanation didn't make sense.