Hiking at a constant rate, Fred covers 20 miles in 4 hours. Predict how far he can hike in 10 hours

Well 20 miles for every 4 hours is 5 miles for every 1 hour.

So just multiply 10 times 5 to get 50. Or do 20 miles x 2 and 4 hours x 2 to get 40 miles in 8 hours then just add the remaining 2 miles which is 10.

Answer is 50 miles.