Alex is riding his bike to a friend's house that is 24 miles away from his home. The scale on Alex's map is 1/2 inch is equivalent to 6 miles. How far is it on the map from Alex's house to his friend's house?
On the map, 1/2 inch is equal to 6 miles.
Therefore, 1 inch on the map is equal to 6 miles * 2 = <<6*2=12>>12 miles.
So, the distance on the map from Alex's house to his friend's house is 24 miles / 12 miles/inch = <<24/12=2>>2 inches. Answer: \boxed{2}.