Take a look at the attached files and use these as a guide or homework check for you assignment that is due soon.
The gradient of a river measures the change in elevation over a certain distance. All rivers flow downhill due to the force of gravity. To calculate gradient, you must find the change in elevation between two locations and divide that by the change in distance.
Since we measure elevation in feet and distance in miles, the units for gradient will be feet per mile (ft/mile).