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21.4601836603....
Assuming the Circles are identical, the red on the left makes up for the missing red of the 10X10 on the right and vice versa.

I was too slow. You're correct.

With approximation Pi = 3.14 ~ 21.5
That was interesting.

The total area of the red spots is 21.5
( triangle area - circle area )

I think the total area of Red Spot is 7.5.

100-25π