Ranjeet bought a book at Rs. 4000. He marked it up by x% above the cost price and then sold it at a discount of 10%. Raghav also bought a book at Rs. 2500 and marked it up by x/2% above cost price and then sold it at a discount of 20%. If the sum of the selling prices of the two books was Rs. 7440, then find the value of ‘x.
A)40 B)50 C)30 D)45 E)35