Six years ago, the ratio of ages of A to B was 7 : 5. After 4 years from now, the ratio of their ages will be 11 : 9. What is A’s age at present?

If A’s income is 40 % less than that of B, how much percent B's income is more than that of A? 

If and , then find the value  of

The monthly income of Shagun and Komal together is Rs.28000. The income of Shagun and Komal is increased by 25% and 12.5% respectively. The new income of Komal becomes 120% of the new salary of Shagun. What is the new income of Shagun?

If , the value of is

A can do of a work in 20 days and B can do of the same work in 15 days. They work together for 10 days. C alone completes the remaining work in 1 day.  B and C together can complete of of the same work in:

(sec A + tan A – 1) (sec A – tan A+1) =?

A can do a work in 6 days and B can do the same work in 12 days. If A, B and C together can do the same work in 4 days, then in how much days C can do it alone?