10,500 mosquitos because 1,000•10hr=10,000 then half of a thousand is 500 so it's that
We have to mutiply factor -2/3 times every agument from the parenthesis.

/+8b
8+6b=-4 /-8
6b=-12 /:6
b=-2 - its the answer
Pic 1 is correct
Pic 2 is correct
Pic 3 is correct