chemistry
posted by ashley on .
Radio waves travel at the speed of light which is 3.00 x 108 m/s. How many minutes does it take for a radio message to reach Earth from Saturn if Saturn is 7.9 x 108 km from Earth?

convert km into m by multiplying by 1000:
(7.9 x 10^8 km)(1000m/1km)
divide by the speed of light:
(7.9 x 10^8 km)(1000m/1km)/(3.00 x 108 m/s)=____s
last, divide by 60 to convert to minutes:
(___s)(1 min/60s)
the key to this problem is the UNITS! notice how I eliminate the units I don't want by finding the equivalent units I wanted. 
44 minutes