A boat's crew rowed \( 16 \) miles downstream, with the current, in \( 2 \) hours. The return trip upstream, against the current, covered the same distance, but took \( 4 \) hours. Find the crew's rowing rate in still water and the rate of the current.
The crew's rowing rate in still water is \(\square\) mile(s) per hour.
The rate of the current is \( \square \) mile(s) per hour.