If $A: B = 3: 4$,$B: C = 4: 5$,and $C: D = 5: 6$,then $A: D$ will be

Seats for Mathematics,Physics and Biology in a school are in the ratio $5:7:8$. There is a proposal to increase these seats by $40\%$,$50\%$ and $75\%$ respectively. What will be the ratio of the increased seats?

The ratio of the number of boys and girls in a school of $720$ students is $7: 5$. How many more girls should be admitted to make the ratio $1: 1$?

Annual income of Amit and Veer are in the ratio $3:2$,while the ratio of their expenditures is $5:3$. If at the end of the year each saves ₹ $1,000$,the annual income of Amit is (in ₹):

The price of a diamond is directly proportional to the square of its weight. $A$ man accidentally broke the diamond into three pieces in the ratio of $3:5:7$ and thus lost ₹ $42600$. What was the original price (in ₹) of the diamond?

Present ages of Sameer and Anand are in the ratio of $5 : 4$ respectively. Three years hence,the ratio of their ages will become $11 : 9$ respectively. What is Anand's present age in years?