AYO HELP ME! which of these mappings is a function?

A.) W
B.) X
C.) Y
D.) Z

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 equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

If you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left