An oil refinery takes 100 L of crude oil as input and after refining for 1 hour gives certain amount of output oil X litres. This can be sold in the market at a profit of Rs 30/L. If this oil is further refined for $$\frac{1}{2}$$ h it gives oil Y litre. This can be sold at a profit of Rs. 50/L. Output and input ratio at both the stages is 90%. The maximum amount that can't be earned from 1000 L of crude input is