Let CP of the table-fan be ₹x.
If SP = ₹891 , Loss % = 10%
CP - Loss = SP
∴x−10x100 = ₹891
⇒100x−10x100 = ₹891
⇒90x100 = ₹891
⇒ x = 891×10090 = ₹990
To make a profit of 20%,
SP = CP + Profit
SP=990+20100×990
SP=990×(1+20100)
SP=990×(1+0.2)
SP=990×(1.2)
∴ SP = 990 × 1.2 = ₹1188