472 to the nearest 100 is 500
3k+10=2k-21
move 2k to the other side
sign changes from +2k to -2k
3k-2k+10=2k-2k-21( combine like terms)
3k-2k+10= -21
k+10=-21
move +10 to the other side
k+10-10= -21-10
k= -21-10
answer:
k= -31
Hi there!

Find the volume of a sphere using the following equation:
V = 4/3πr³
Substitute in the given radius:
V = 4/3π(1)³
V = 4/3π or ≈ 4.19 units³
You would do 21 divided by 3 and get 7.
The answer is 7 kids are in the line.
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