Question

The average age of a man and her daughter is 40 yrs the ratio of their ages is 6:2 then what is the daughter age in yrs

Answer 1

let the age of a man and her daughter be x and y

x+y/2=40
x+y=80...(1)

x=6
y...2

2x=6y
2x-6y=0.....(2)

multiplying (1) by 6
6× x+y=80...(1)
6x+6y=480.......(3)

adding 2 and 3

2x-6y=0.

6x+6y=480
8x=480
x=60

6x+6y=480
360+6y=480
6y=120
y=20


hence, the daughter's age in years is 20