<B is complement of <A

<C is a supplement of <B
<D is a supplement of <c
<E is a complement of <D
<F is a complement of <E
<G is a supplement of <F

Then <G is congrugent <?

G = 180-F

= 180-(90-E) = 90+E
= 90+(90-D) = 180-D
= 180-(180-C) = C