At an upstream location on a river the flow is 75 m and at a downstream location it is 100 ms. In one hour the

At an upstream location on a river the flow is 75 m³ and at a downstream location it is 100 m³s. In one hour the storage in the river redaces by 65,000 m². If the upstream flow after one hour is 100 m³s, what is the down or after one hour?