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
Answer:

Step-by-step explanation:
Swap the fraction,

or around 7.142...
The predicted time remaining has decreased by 30 years, so the second one would be the answer
The answer is 5:) you first have to cross multiply then divide both sides from x
Answer:
the answer would be (7,5)