unable to understand this question question-11 and 12

unable to understand this question question-11 and 12

unable to understand this question Ribhu adds ‘a’ litres of water to pure milk to prepare 26 litres of milk-water mixture. He sells this mixture at 10% higher price than the original cost price (in Rs./litre) of milk and earns a profit of 43% on this transaction. If he adds ‘a’ litres of water to 30 litres of pure milk and sells the resulting mixture at the original cost price(in Rs./litre) of milk, then what is his profit percentage in this transaction? (Assume that water comes free of cost).(If required, round of your answer to nearest integer % for example 32.32% will be 32.)

unable to understand this question Ribhu adds ‘a’ litres of water to pure milk to prepare 26 litres of milk-water mixture. He sells this mixture at 10% higher price than the original cost price (in Rs./litre) of milk and earns a profit of 43% on this transaction. If he adds ‘a’ litres of water to 30 litres of pure milk and sells the resulting mixture at the original cost price(in Rs./litre) of milk, then what is his profit percentage in this transaction? (Assume that water comes free of cost).(If required, round of your answer to nearest integer % for example 32.32% will be 32.)

unable to understand this question not able to understand the method of solving the question