If the total demand in E is 80% of demand in A, what is the demand in A?

Answer: Option A

The total demand in E = Total input into E.
  → 550 + 800 + 650 = 2000
$$\begin{array}{rl}& =\frac{2000\times 100}{80}\\ & =2500\end{array}$$
Hence, the demand in A will be 2500.