Question

If 4 is subtracted from the numerator of a fraction, its value becomes 1/3. If 5 is added to the denominator of the original fraction its value becomes 1/2. What is the original fraction. ​

Answer 1

79

Explanation:

Let the numerator of the original fraction be 'x' and the denominator be 'y'. So, the original fraction becomes xy

According to the question,

Condition I,

If 4 is subtracted from the numerator of a fraction, its value becomes 1/3.

or,x−4y=13

or,3(x−4)=y

or,y=3x−12

Condition II,

If 5 is added to the denominator of the original fraction, the value becomes 1/2.

or,xy+5=12

or,2x=y+5

Put value of y from equation (i) in equation (ii), we get,

or,2x=(3x−12)+5

or,2x=3x−12+5

or,3x−2x−7=0

∴x=7

Put value of x in equation (i), we get,

or,y=3×7−12

or,y=21−12

∴y=9

So, (x,y) = (7,9)

Therefore, the required original fraction is 79.