You row a boat perpendicular to the shore of a river that flows at 3 m/s. The velocity of your boat is 4 m/s relative to the water. What is the velocity of your boat relative to the shore?

Unpolarized light passes through three polarizing filters. the first one is oriented with a horizontal transmission axis, the second filter has its transmission axis 25.7° from the horizontal, and the third one has a vertical transmission axis. what percent of the light gets through this combination of filters