12) the radius is 15 so with the equation (3.14)*r^2, we get (3.14)(15^2)=706.5
13) true, true (if x=4), true
14) y=0.75x+4.50, $8.25
To find this you would do 800 + 15x where x is the amount of years.
For 9 years it would be 800 + 15(9) which is 800 + 135.
At the end of 9 years, the apartment's rent would be $935. I hope that's utilities included because... yikes...
The answer is 360 hope it helps