Ok if you can figure this out right your legend

If the speed of an electromagnetic wave is 100,000 cm/s and its wavelength is 100 cm, what is its frequency? a) 100,000 cycles per second (hz) b) 1 × 10-3 cycles per second (hz) c) 10,000,000 cycles per second (hz) d) 1,000 cycles per second (hz)

Which number produces a rationale number when multiplied by 1/5

Can someone check if i did this correct. it’s number 4 if you’re wondering.