If the selling price of $40$ articles is equal to the cost price of $50$ articles, the loss or gain percent is

A merchant advertises $10 \%$ off on the items bought from his store. The total discount got by a customer who bought a cooker worth $Rs.\,650,$ a heater worth $Rs.\,500$ and a bag worth $Rs.\,65$ is (in $Rs.$)

The cost price of $6$ pens is equal to the selling price of $4$ pens. Find the profit percent.

A man buys $100\, kg$ of sugar for $Rs.\, 2400 .$ He sold $1 / 4$ th of the stock at a loss of $5 \% .$ At what per cent profit should he sell the remaining stock so as to make an overall profit of $20 \%$ on the whole transaction? (in $\%$)

A person earns $15 \%$ on investment but loses $10 \%$ on another investment. If the ratio of the two investments be $3: 5,$ what is the gain or loss on the two investments taken together in $\%$?

Mr. Kapur purchased two toy cycles for $Rs. 750$ each. He sold these cycles, gaining $6 \%$ on one and losing $4 \%$ on the other. The gain or loss percent in the whole transaction is