Tell whether x and y are proportional

Prove that 3: 8 is equivalent to 12: 32.a. use diagrams to support your answer.

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)

15/16 as a decimal rounded to the nearest hundredth