Loss% =LossC.P×(..............) . [100/SP].
If a product is sold at a lesser price than the price at which it was bought, then the loss occurs.
Loss% is calculated on the basis of cost price.
Loss%=LossC.P×100.
Hence, the answer for given blank is 100.
Find Profit or loss percent, if C.P=Rs100;S.P=Rs90