Let total investment = (80 × 73)Income from 15% at 80Income on investing 80 = Rs 15Income on investing (80 × 73) =80×80×7315 = Rs 1,095Income from 1351% at 73= Income on investing 73 = Rs 566Income on investing (80 × 73) =566×731×80×73 = Rs 1,056Required difference = 1,095 - 1,056 = Rs 39