The type of wave that does not need matter to carry energy is an electromagnetic wave. Examples of electromagnetic waves include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.
As for the second question, we can use the direct variation formula:
y = kx
where k is the constant of variation. We can solve for k by plugging in the given values:
20 = k(6)
k = 20/6
Now that we know k, we can use it to solve for y when x = 24:
y = (20/6)(24) = 80
Therefore, the value of y when x = 24 is 80, which is option B.