A merchant sold his goods for Rs. 75 at a profit percent equal to C.P. The C.P was:________?

A. Rs. 40
B. Rs. 50
C. Rs. 60
D. Rs. 70
Explanation:
Let C.P = Rs. X
X + X% of X = 75
X2 + 100 X – 7500 = 0 Or (X+ 150) (X – 50) = 0
X = 50 (neglecting X= – 150)