1984 年

If $\dfrac{3x+2y}{x+5y}=1$, then $\sqrt{x+y}:\sqrt{x-y}=$

$A$ is $25\%$ taller than $B$. $B$ is $25\%$ shorter than $C$. $A$'s height : $C$'s height $=$

A rectangular box, without a lid, is 40 cm long, 30 cm wide and 10 cm high. The area of the external surface of the box is

A man drives a car at 30 km/h for 3 hours and then at 40 km/h for 2 hours. His average speed for the whole journey is

$A$ alone can complete a job in 8 hours. $B$ alone takes 12 hours and $C$ alone takes 6 hours. After $A$ and $B$ have worked together on the job for 3 hours, $C$ joins them. How much longer will they take to complete the job?

The marked price of a book is $20\%$ above the cost price. If the book is sold at a discount of $10\%$ off the marked price, what is the gain per cent based on the cost price?

$\dfrac{\tan^2\theta}{1+\tan^2\theta}+\cos^2\theta=$

In the figure, $BCD$ is a straight line. $\angle ADC=90^\circ$ and $BC=10$. $AD=$

In the figure, $\cos\theta=$

In the figure, $\triangle ABC$ lies in a horizontal plane. $\angle BAC=90^\circ$. $HA$ is vertical and $HA=h$. $\tan\theta=$