If 2x + 3y = 87 and 3x – 3y = 48, what is the value of x?

If a\b + b\a =1, then the value of a³+b³ will be 

A boat running downstreams covers a distance of 30 kms in 2 hours. While coming back the boat takes 6 hours to cover the same distance. If the speed  of the current is half that of the boat, what is the speed of that boat in kmph?

A work could be completed in 100 days by some workers. However, due to the absence of 10 workers, it was completed in 110 days. The original number of workers was

A bag contains Rs.90 in coins of denominations of 50 paise, 25 paise and 10 paise. If coins of 50 paise, 25 paise and 10 paise are in ratio 2 : 3 : 5, then the number of 25 paise coins in the bag is 

The area of triangle is half the area of square. The perimeter of the square is 224 cm. What is the area of triangle?

A certain sum of money lent out at simple interest amounts to Rs. 2400 in 4 years and Rs. 3000 in 6 years. Find the rate of interest per annum?

If a : b = 20:5 then find out the value of (13a-9b): (11a-7b)?