help coordinates

The area is 47*pi

Isolate the constant: $x^2 + y^2 + 5x - 5y = 18$

Rearrange as follows: $(x^2 + 5x) + (y^2 - 5y) = 18$

Add 6.25 to complete the square on x, and add another 6.25 to complete the square on y. 

This gives: $(x+2.5)^2 + (y-2.5)^2 = 30.5$.

Note that the constant (30.5) is $r^2$, meaning the area of the circle, in terms of pi, is $\color{brown}\boxed{{30.5 \pi}}$