Could someone me understand how to solve this , you!

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)

3x + 4y = 5 x- 3y = -7 solve by substitution

Find the ratios of the corresponding sides