If the average of a and b is 45, and the average of b and c is 35 then (a-c)=?
A
5
B
10
C
20
D
30
Correct Answer: 20
এখানে, a + b = 45×2 = 90 - - - - - - - (1)এবং b + c = 35×2 = 70 - - - - - - - - (2)(1) - (2) হতে পাই (a + b - b - c) = 90 - 70⸫ a - c = 20