30 pens and 75 pencils altogether were purchased for Rs .510. If the average price of a pencil was Rs. 2, what was the average price of a pen? 

The average age of 30 students of a class is 15 years. A 20-year-old student left the class and replaced by two new students, whose age difference is 5 years. If the average age of all students is 15 years, then what will be ratio of young student to elder students. 

The average marks of 42 students in an examination, were 64. Later it was found that the marks of three students were misread as 72, 58 and 44 instead of the actual marks 64, 42 and 26 respectively. What are the correct average marks?

A batsman makes a score of 87 runs in the 17^th match and thus  increases his average by 3. Find his average after 17^th match.

In an examination, 40% of the candidates write their answers in Urdu and the rest in Marathi. The average marks of the candidates writing in Urdu is 74 and the average marks of the candidates writing in Marathi is 77. What are the average marks of all the candidates? 

Find the average of the following set of numbers.
132, 148, 164, 128, 120, 136

The average monthly income of A and B is Rs.15,050 , and the average monthly income of B and C is Rs.15,350 and the average income of A and C is Rs.15,200. The monthly income of A is.