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 $Rs.$)

Sardar singh bought $200$ dozen oranges at $Rs.\,10$ a dozen. He spent ₹500 on transportation. He sold them at $Rs.\,1$ each. What was his profit or loss percent?

A man had a certain amount with him. He spent $20 \%$ of that to buy an article and $5 \%$ of the remaining on transport. Then he gifted $Rs.\,120.$ If he is left with $Rs.\,1,400$ the amount he spent on transport is (in $Rs.$)

A shopkeeper bought $30\, Kg$ of wheat at the rate of $Rs.\,45$ per $Kg.$ He sold $40\%$ of the total quantity at the rate of $Rs.\,50$ per $Kg.$ Approximately, at what price per $Kg$ should he sell the remaining quantity to make $25$ percent overall profit? (in $Rs.$)

If a shopkeeper wants to give $20 \%$ discount on a toy, he has to sell it for $Rs.\,300.$ If he sells it at $Rs.\,405,$ then his gain percent is