I really need the answer for this and how you got it please!

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)

Find the midpoint m of z1=(8+5i) and z2=(12+3i)

Does anyone know how to solve and graph this: 4 + | a + 2 | < 7the only part i don't get is the "4 +"