Hey, Melany. To answer this problem, simply set up a proportion:
. Now let's solve for x.
- Cross multiply:
- Isolate x:

This means that x = 24.
There are 24 9th graders in the band.
The awnser of the question is B
600 grams = 0.6 kilograms
0.6 x 4 = 2.4 kilograms
What form do you need it in?