There is no definitive answer to this question as it depends on a number of factors, such as the strength and direction of the current, the wind speed and direction, and the width and depth of the river. However, there are some general tips that can help you paddle faster upstream.
Firstly, it is important to choose a route that will minimize resistance from the current. This means avoiding areas where the water is shallow or has a lot of debris. It is also helpful to find a section of river with few bends, as this will reduce the amount of time you spend paddling against the current.
Secondly, it is important to use your paddle effectively in order to maximise your speed. When paddling against the current, it is best to use a wide stroke which provides more power. It is also important to ensure that your paddle enters and exits the water at roughly the same point in order to minimize resistance.
Finally, it is important to maintain a good body position when paddling upstream. This means keeping your back straight and your head up in order to avoid tiring yourself out too quickly. It can also be helpful to lean slightly forward in order to increase your balance and stability.