If the ratio of the cost price and selling price of an article is $20: 21,$ then what will be the profit percent?

A shopkeeper sold an article offering discount of $5 \%$ and earn a profit of $23.5 \% .$ What would have been the percentage of profit earned if no discount has been offered?

A trader sells his table at a profit of $15 \%$ and the chair at a loss of $7 \frac{1}{2} \%,$ but on the whole he gains $Rs.\, 50 .$ If he sells the table at a loss of $7 \frac{1}{2} \%,$ and chair at a profit of $15 \%,$ then he neither gains nor loses. Find the cost price of the table

A sells his house worth $Rs.\, 10\, lakh$ to $B$ at a loss of $10 \% .$ Later $B$ sells it back to $A$ at $10 \%$ profit. The result of the two transactions is

A trader purchase a wrist watch and a pendulum for $Rs.$ $390.$ He sells them making a profit of $10 \%$ on the watch and $15 \%$ on the pendulum. He earns a profit of $Rs$. $51.50 .$ The difference between the original prices of the pendulum and the watch is equal to? (in $Rs.$)

A discount dealer professes to sell his goods at cost price but uses a weight of $960\, gms$ instead of a $Kg$ weight. Find his gain $\% ?$