Present age of Bob is equal to Abby's age $8\, years$ ago. Four years hence, the respective ratio between Bob's age and Abby's age will be $4: 5$ at that time. What is Bob's present age? (in $years$)

A shopkeeper sells two watches for $Rs.\, 308$ each. On one he gets $12 \%$ profit and on the other $12 \%$ loss. His profit or loss in the entire transaction was

A fair price shopkeeper takes $10 \%$ profit on his goods. He lost $20 \%$ goods during theft his loss $\%$ is

Successive discounts of $10 \%, 12 \%$ and $15 \%$ amount to a single discount of

A man bought $500$ metres of electronic wire at $50$ paise per metre. He sold $50 \%$ of it at a profit of $5 \%$ At what percent should he sell the remainder so as to gain $10 \%$ on the whole transaction?

The marked price of an article is $Rs.\, 5000.$ But due to a special festive offer a certain per cent of discount is declared. Mr. $X$ availed this opportunity and bought the article at reduced price. He then sold it at $Rs.\, 5000$ and thereby made a profit of $11 \frac{1}{9} \%$. The percentage of discount allowed was