(b) 1800 g
Let the original stock of rice be x kg.
Parts of the stock sold first time = \(\bigg(\frac{2x}{3}+100\bigg)\) kg
∴ Remaining stock = \(\bigg[x-\bigg(\frac{2x}{3}+100\bigg)\bigg]\) kg
= \(\big(\frac{x}{3}-100\big)\)kg
Part of the stock sold second time
= \(\bigg[\frac12\bigg(\frac{x}3-100\bigg)+100\bigg]
\)
= \(\bigg(\frac{x}{6}-50+100\bigg)\) kg = \(\big(\frac{x}{6}+50\big)\) kg
∴ Remaining stock = \(\big(\frac{x}{3}-100\big)\) - \(\big(\frac{x}{6}+50\big)\)
= \(\big(\frac{x}{3}-\frac{x}6-100-50\big)\) kg
= \(\big(\frac{x}{6}-50\big)\) kg
Given, \(\frac{x}{6} - 150 = 150 ⇒ \frac{x}{6}=300 ⇒x=\) 1800 kg.