A earns 50% of B's salary, B earns 80% of C's salary. If the total earnings for a month is Rs. 22000, then what is the earning for A ?

Let C's salary be Rs. x

Then B's salary = 80x/100

=> A's salary = (50/100) * (80x/100) = 40x/100

But given total earnings in a month = 22000

=> x + 80x/100 + 40x/100 = 22000

=> x + 120x/100 = 22000

=> x = 10000

=> A's salary = 40 x 10000/100 = Rs. 4000