The length of a rectangle increases by $20 \%$ and the breadth by $30 \%$. Then the perimeter of the rectangle will increase by:

An army lost $10 \%$ of its men in war,$10 \%$ of the remaining died due to disease,and $10 \%$ of the rest were declared disabled. Thus,the strength of the army was reduced to $7,29,000$ active men. What was the original strength of the army?

If in an examination $20 \%$ students failed in Hindi,$25 \%$ failed in English,and $7 \%$ failed in both subjects,then what is the percentage of students who failed in at least one of the subjects (in $\%$)?

Anil's monthly income is $30 \%$ more than Ashok's. Ashok's monthly income is $10 \%$ less than Manoj's. If the difference between the monthly income of Anil and Manoj is $₹ 1360$,what is the monthly income of Ashok?

On decreasing the price of a colour $TV$ by $30 \%$,its sale is increased by $20 \%$. The effect on the revenue is:

Neha has a watch which gains $2 \%$ per hour when the temperature is in the range of $40^{\circ}C - 50^{\circ}C$ and it loses at the same rate when the temperature is in the range of $20^{\circ}C - 30^{\circ}C$. The watch runs on time in all other temperature ranges. On a sunny day,the temperature started rising from $8$ $a.m.$ at a uniform rate of $2^{\circ}C$ per hour and during the afternoon it started falling at the same rate. Find what time will it be by the watch at $7$ $p.m.$ if at $8$ $a.m.$ the temperature was $32^{\circ}C$ and at $4$ $p.m.$ it was $40^{\circ}C$?