एक वस्तु को 750 रुपये में खरीदा जाता है और 1000 रुपये में बेचा जाता है। लाभ प्रतिशत ज्ञात कीजिए।

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?