Two years ago father was three times as old as his son and two years hence twice his age will be equal to five times that of his son.find their present
age.(don't use x and y two variable,use only one variable)
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Answered by
2
using one variable.
Let age of Son two years ago be = Son.
Then father's age two years ago was = 3 * Son
Son's age two years hence (after the present ) = Son + 4
Father's age after two years hence = 3 * Son + 4
hence, 2 * (3 * Son + 4) = 5 ( Son + 4)
Son = 12
Son was 12 years old , two years ago. Hence father was 36 yrs old.
They are now 14 years and 38 years old.
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using two variables:
two years ago:
Father - 2 years = 3 * ( son - 2 years)
=> Father = 3 * son - 4 --- equation 1
after two years from now , in future
2 * (father + 2 years ) = 5 * (son + 2 years)
=> 2 * father = 5 * son + 6 --- equation 2
Multiply equation 1 by 2 and subtract equation 2 from it:
0 = son - 14 => son is 14 years old now
Father = 3 * 14 - 4 = 38 years now
Let age of Son two years ago be = Son.
Then father's age two years ago was = 3 * Son
Son's age two years hence (after the present ) = Son + 4
Father's age after two years hence = 3 * Son + 4
hence, 2 * (3 * Son + 4) = 5 ( Son + 4)
Son = 12
Son was 12 years old , two years ago. Hence father was 36 yrs old.
They are now 14 years and 38 years old.
============================================
using two variables:
two years ago:
Father - 2 years = 3 * ( son - 2 years)
=> Father = 3 * son - 4 --- equation 1
after two years from now , in future
2 * (father + 2 years ) = 5 * (son + 2 years)
=> 2 * father = 5 * son + 6 --- equation 2
Multiply equation 1 by 2 and subtract equation 2 from it:
0 = son - 14 => son is 14 years old now
Father = 3 * 14 - 4 = 38 years now
raviverma02486:
thanks
Answered by
0
Let age of Son two years ago be = Son.
Then father's age two years ago was = 3 × Son
Son's age two years hence (after the present ) = Son + 4
Father's age after two years hence = 3 × Son + 4
Hence, 2 × (3 × Son + 4) = 5 ( Son + 4)
6Son + 8 = 5Son + 20
Son = 20 - 8
Son = 12 years
Son was 12 years old , two years ago. Hence father was 36 years old.
Present age of Son = 14 years . Present age of father = 38 years.
Then father's age two years ago was = 3 × Son
Son's age two years hence (after the present ) = Son + 4
Father's age after two years hence = 3 × Son + 4
Hence, 2 × (3 × Son + 4) = 5 ( Son + 4)
6Son + 8 = 5Son + 20
Son = 20 - 8
Son = 12 years
Son was 12 years old , two years ago. Hence father was 36 years old.
Present age of Son = 14 years . Present age of father = 38 years.
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