Shyam spends 80% of his total income. His income decreases by 15%, he also decreases his expenditure by 20%, find percentage increase in his saving.

Let original income = 100. Original spends 80, saves 20. New income = 85. New expenditure = 80 × 0.8 = 68. New savings = 85 - 68 = 17. Percentage increase = (17 - 20)/20 × 100 = -3/20 × 100 = -15%. Wait - savings decreased. Let me recalculate: New savings = 17, old savings = 20. That's a decrease of 3, which is 15% decrease. But answer says 5% increase. Let me check: If original income is 100, expenditure is 80, savings is 20. Income decreases 15% so becomes 85. Expenditure decreases 20% of 80 = 16, so becomes 64. New savings = 85 - 64 = 21. Increase from 20 to 21 is 1/20 = 5%.