A number if required by 25% becomes 225. By what percent should be increased so that it becomes 375?

15 litres of a mixture contains alcohol and water in the ratio 1 : 4 , If 3 litres of Water is mixed in it , the percentage of alochol in the new mixture will be : 

Some students (only boys and girls) from different schools1 appeared for an Olympiad exam. 20% of the boys and 15% of the girls failed the exam. The number of boys who passed the exam was 70 more than that of the girls who passed the exam'. A total of 90 students failed. Find the number of students that appeared for the exam.

A number, on subtracting 15 from it reduces to its 80 %. What is 40 % of the number? 

In a school, number of girls is 75% of number of boys. Difference between boys and girls is 30. On a particular day 20% girls were absent, then find the number of girls those who present? 

A businessman bought an article and sold it at a loss of 5%. If he had bought it for 10% less and sold it for Rs. 33 more, he would have had a profit of 30%. The cost price of the article is 

The difference of two numbers is 15 % of their sum. the ratio of the larger number to the smaller number is: 

A’s income is 60% of B’s income, and A’s expenditure is 70% of B’s expenditure. If A’s income is 75% of B’s expenditure, find the ratio of A’s saving to B’s saving?