$6\mathrm{.}11$ How many return values may a function have?

$6\mathrm{.}12$ Write a header for a function named distance. The function should return a

double and have two double parameters: rate and time.

$6\mathrm{.}13$ Write a header for a function named days. The function should return an

int and have three int parameters: years, months, and weeks.

$6\mathrm{.}14$ Write a header for a function named getkey. The function should return a

char and use no parameters.

$6\mathrm{.}15$ Write a header for a function named lightYears. The function should

return a long and have one long parameter: miles.