First find the radius of the big circle
The diameter of the first circle + d of second smaller circle /2
(10*2)+(4*2)/2= 20+8/2 = 28/2 = 14 this is the radius of the biggest circle!
Now thaw we know the radius of the biggest circle we can subtract the area of it from the smaller two so:
(14^2 pi) - ( (10^2 pi) + (4^2 pi) ) = 80 pi = 251.32 cm^2
(Mark me the brainliest if this has helped)