SOLUTION: 5 years ago radha age was 7 tymes of her daughter.her age will be 3 tymes of her daughter in 5 years.then what is the age of radha?

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Question 726445: 5 years ago radha age was 7 tymes of her daughter.her age will be 3 tymes of her daughter in 5 years.then what is the age of radha?
Answer by mananth(16946) (Show Source):
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let daughter's age =x
Radha's age =y
5 years ago
y-5=7(x-5)
y-5=7x-35
y-7x=-30........................(1)
5 years later
y+5=3(x+5)
y+5=3x+15
y-3x=10.........................(2)
Eliminate y
multiply (1)by -1
Multiply (2) by 1
7 x -1 y = 30
-3 x + 1 y = 10
Add the two equations
4 x = 40
/ 4
x = 10
plug value of x in (1)
-7 x + 1 y = -30
-70 + y = -30
y = -30 + 70
y = 40
y = 40
x= 10
y= 40
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