The average of a,b,c is 20 and that of b,c,d is 25, if d=30, then the value of a is-

Of the three numbers whose average is 60, the first is one-fourth of the sum of the whole number. The first number is: 

Average of 21 number is 36. If the average of first 12 numbers is 15, then find the average of remaining 9 number?

The average salary per head of all the workers of JK Campus is ₹ 60. The average salary of 12 center heads is ₹ 400 and of the rest is ₹ 56. The total number of workers in JK Campus is 

The average of 5 numbers, arranged in a row, is 309. The average of the first two of these numbers is 431 and the average of the last two of these numbers is 231.5. What is the value of the number at the center of the row?

A librarian purchased 60 story books for his library. But he found that he could get 4 extra books by spending Rs. 336 more and then the overall average price per book would be reduced by Re 1. The previous average price of each book was 

If (a + b): (b + c): (c + a) = 5: 6: 9 and a + b + c = 10. What is the value of c?

The average of runs scored by a cricketer in his 99 innings is 99. How many runs will he have to score in his 100th innings so that his average of runs in 100 innings will become 100?