More people walk to school or work hope this helps
Answer:
Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space.
Explanation:
Well, the lines of workings are cut off in the middle, and there's no 2nd image.
But I think it must have to do with the "cos" terms at the right end of the picture.
I'm guessing now, because the part I'm interested in would be just past the edge, where we can't see it.
I <em>think</em> that the first line says "cos(some angle)", and at the same place in the second line it says "cos(180 - the same angle)".
If that's what it says, then that's your answer, because cos(anything) is equal to the <em>negative</em> of cos(180 - the same thing).
That's the best I can do for you just now. Honestly, I don't see the connection yet between the question Dave is working on and the two lines I see in the picture.
B. How many people were included in the study.