Area of a circle using the radius is pi*r^2, so:
A=3.14*4^2
A=3.14*16
A=50.24
Move over 2 decimal places
This would be 38.4%
all you have to do is see whether both variables of each point meet both contraints:
for a) 1<3 and 2>1 is true so a is a solution to the system