To find out how many square feet Ivan can paint in 3 hours, we first need to determine how many half-hour increments there are in 3 hours.
3 hours = 3 hours × 2 (half hours per hour) = 6 half hours
Since Ivan can paint 25 square feet in each half hour, we can now calculate the total amount he can paint in 6 half hours:
Total square feet painted = 25 square feet/half hour × 6 half hours = 150 square feet
Therefore, Ivan can paint 150 square feet in 3 hours.