Question

Find ages of Aand B are in the ratio 5:7 .four years from now the ratio of their present ages will be 3:4 .find their parents age??​

Answer 1

Given:-

• Ratio of ages 5:7
• after four years 3:4

To find:-

• There present age

Solution:-

If ages are in ratio than we can take there ages as xA and xB

• So age of a=5x
• age of b=7x

Four years later there ages will become

• a's age after four year = 5x+4
• b's age after four year=7x+4

Now after four years age ratio is again given as 3:4 so now:-

$\huge \frac{5x + 4}{7x + 4} = \frac{3}{4}$

$\large \:( 5x + 4) \times 4 = 3(7x + 4)$

$\large20x + 16 = 21x + 12$

$\large \: x = 4$

As we assumed a's age as 5x and b's age as 7x hence there present ages :-

• a=20years
• b=28years