$(11-21)$ A car is moving at a constant velocity of $110$ km$/$h$.$ Determine the upstream velocity to be used in fluid flow analysis if $($a$)$ the air is calm, $($b$)$ wind is blowing against the direction of motion of the car at $30$ km$/$h$,$ and $($c$)$ wind is blowing in the same direction of motion of the car at $30$ km$/$h$.$