Answer:
50mph
Explanation:
Speed (v) is equal to distance (d) divided by time (t)
so we have the formula

Adrian needs to be at his grandmother's house in 3 hours so

His grandmother's house is 150 miles away so

now we can plug these values into our formula and we get


So, Adrian needs to drive at 50 miles per hour to get to his grandmother's house in three hours.