The answer is K= 7 because
-5-7=-12
I'm not exactly sure what you're asking but in total there's 800 kids at East Side Elementary School.
Answer:

Step-by-step explanation:

Answer:
add 5 then multiply by 1/2
Step-by-step explanation:
Twice a number is 2n.
The difference of twice a number and five 2n - 5.
The difference of twice a number and five is three. 2n - 5 = 3
2n - 5 = 3
2n - 5 + 5 = 3 + 5 (1) add 5
2n = 8
1/2*2n = 1/2*8 (2) multiply by 1/2
n = 4