New expenditure = Original expenditure × (1+ Increase in expenditure ) Let the original consumption be 100 litres. Let the reduced consumption be x litres. New expenditure = New price × Reduced consumption Calculation: Let the original price be ₹1 per litre (for simplicity). Original expenditure =100×₹1=₹100 New price =₹1+85% of ₹ 1=₹1+₹0.85=₹1.85 New expenditure =₹100+48% of ₹ 100=₹100+₹48=₹148 New expenditure = New price × Reduced consumption ⇒₹148=₹1.85×x ⇒x=
148
1.85
⇒x=80 Therefore, the consumption should be reduced by 100−80=20%.