Convert hours into minutes.

The correct answer is: 210

hr = 3 × 60 + × 60 = 180 + 30 = 210 min

3 ½ = (3 x 2 + 1)/2 = 7/2 hours.
1 hour = 60 minutes.
7/2 hours = 7/2 x 60 = 210 minutes.