The question appears to be incomplete.

A picture helps. In each case the area measure is square units. The radius of the smaller circle is 5 units, so its area is

a

a

a

A picture helps. In each case the area measure is square units. The radius of the smaller circle is 5 units, so its area is

a

_{0}= π*r^2 =**25π**The radius of the larger circle is 10 units (the diameter of the smaller circle), so its area isa

_{1}= π*10^2 =**100π**The remaining area of the larger circle, after the smaller circle is cut out, isa

_{1}- a_{0}= π(100 - 25) =**75π**