What is 309,099,990 i’m expanded form

The level of co2 emissions, f(x), in metric tons, from the town of fairfax x years after they started recording is shown in the table below. x 2 4 6 8 10 f(x) 26,460 29,172.15 32,162.29 35,458.93 39,093.47 select the true statement.

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?

How can (square root of 25) ^2 be rewritten?