The answer is 4x + 4y
Solve for the area of the circular region first:
A = pi*r^2
A = pi*(30 mi)^2
A = 2827.43 mi^2
Density = 70000 people/2827.43 mi^2
Density = 24.76 = 25 people/mi^2 <--ANSWER Plz vote brainnliest