Division of lots for sale

because you only know the ratio of the BCD, but not compared to the blank area or A.

First, do NOT think that diagram is proportion to the actualy size.

Let's use your logic.

We know that A and B alone is not sufficient, so we'll ignore that.

Combining them together, you have

Total area - 1600
A - 800
We'll call the blank "U"

we know that "U" + B+C+D = 800
from first statement, we know that C=2D, B=2Cor4D.

GREAT! So we know the details of the 3

Let's plug in some numbers.

if B was 100, then C=50 and D = 25, that works our math right?
so now you have "U" = 800-(50+25+100) = 625

or.. how about B = 200, then C = 100, D = 50, now our "U" is 450.

Hence, E

We either need to know the actualy size of "U" or ratio of "U" to any other area.

Thanks hwiya