यदि 840 रुपये अंकित मूल्य वाली एक वस्तु को 714 रुपये में बेचा जाता है, तो छूट का प्रतिशत क्या है?

A person saves 90% of his income. If his expenditure is ₹520, find his income (in ₹).

By how much is 30% of 60 greater than 25% of 40?

By how much is 30% of 50 greater than 35% of 30?