Set up a proportional equation. We know that the total area of a circle is:
A=πr^2, knowing that we are only using 120° out of the whole 360° we can say that the area of the sector is:
A=πr^2(120/360)
A=(πr^2)/3, and since we are told that WX which is r, is 15 ft we can say:
A=(π15^2)/3
A=225π/3
A=75π ft^2