For part (a): ##c = 1.079 * 10^(9)km/h##

For part (b): ##c = 1.118 * 10^7mi/min##

To solve this problem you need to be familiar with several conversion factors. More specifically you need to know that

##1 km = 10^3m##

##1 h = 60 min ##and ## 1 min = 60 s##

##1 mile = 1.609344 km##

SO for part (a) you need to go from meters to kilometers and from seconds to minutes then to hours.

##2.998 * 10^(8)color(red)(cancel(color(black)(m)))/color(red)(cancel(color(black)(s))) * 1 km/(10^3color(red)(cancel(color(black)(m)))) * (60color(red)(cancel(color(black)(s))))/(1color(red)(cancel(color(black)(min)))) * (60color(red)(cancel(color(black)(min))))/(1color(red)(cancel(color(black)(h)))) = 10792.8 * 10^(5)km/h##

Rounded to four the number of sig figs you gave for the speed of light in meters per second the naswer will be

##c = color(green)(1.079 * 10^(9)km/h)##

Now for part (b). Now you need to go from meters to kilometers then to miles and from seconds to minutes.

##2.998 * 10^(8)color(red)(cancel(color(black)(m)))/color(red)(cancel(color(black)(s))) * (1color(red)(cancel(color(black)(km))))/(10^3color(red)(cancel(color(black)(m)))) * 1 mile/(1.609344color(red)(cancel(color(black)(km)))) * (60color(red)(cancel(color(black)(s))))/1 min = 111.77 * 10^(5)mi/min##

Once again round the answer to four sig figs

##c = color(green)(1.118 * 10^7mi/min)##