The ratio of 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 ?

If $$ {y\over {x-3}}={y+x\over 3}={x\over y}$$ then 3 : y : x equal to :

If a + b: b+c : c+a= 6:7:8 and a + b+c= 14, , then the value of c is : 

A and B started business with the initial investment in the ratio 12:11 and their profit in the business were 4x and x respectively. If A invested the money for 11/12 year, then B invested the money for?

 If $$ {x\over y}={y\over w}$$ then what is the value of (xy+zw).

If $$ {y\over x-z}={y+x\over z}={x\over y}$$ the find x:y:z is?

The ratio of investment by A to that by B in a business is 14 : 15 and the ratio of their respective profit at the end of a year is 2 : 5. If A invested the money for 3 months, then for how much time ( in months) B invested his money?

If (a+b) : (b+c) : (c+a) = 7 :6 : 5 and (a+b+c)=27, then what will be the value of $$ {1\over b}:{1\over a}:{1\over c}$$.