maths gain

[enthada]

A building with height D shadow up to G. A neighbor building with what height shadows C feet.

[pquinlan]

If "shadow up to G" means "shadow with length G" the answer is (CxD)/G

Draw 2 right angle triangles of same shape (roughly, for visualisation) but different size, with horizontal base and vertical on the left.

First one, vertical ht is G, first building ht, base is G, shadow length.

Second one, call vertical ht A, C is base, shadow length.

Triangles are "similar", meaning D/G = A/C

So A = (DxC)/G

[pquinlan]

Typo in my answer:

First one, vertical ht is D, not G.

Ooops! Hope its clear and of help.