five years ago A mother was 7 times as old as her daughter five years hence she will be 3 times as old as her daughter find their present ages
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Let present age of daughter and her mother be X and Y year's.
Five year's ago age of daughter = ( X - 5 ).
Five years ago age of her mother = ( Y - 5 ).
According to the question,
Y - 5 = 7 ( X - 5 )
Y - 5 = 7X - 35
7X - Y = 35 - 5
7X - Y = 30 ----_-----(1)
Five years hence age of daughter = ( X + 5 ).
Five years hence age of mother = ( Y + 5 ).
According to the question,
Y + 5 = 3 ( X + 5 )
Y + 5 = 3X + 15
3X - Y = 5 - 15
3X - Y = -10 -----------(2)
From equation (1) , we get
7X - Y = 30
Y = ( 7X - 30 ) --------(3)
Putting the value of X in equation (2) ,
3X - Y = -10
3X - ( 7X - 30 ) = -10
3X - 7X + 30 = -10
-4X = -10 - 30
-4X = -40
X = 10
Putting the value of X in equation (3) ,
Y = ( 7X - 30 ) = ( 7 × 10 - 30 )
Y = 70 - 30 = 40 years.
Hence,
Present age of daughter = X = 10 year's.
and,
Present age of mother = Y = 40 years
Five year's ago age of daughter = ( X - 5 ).
Five years ago age of her mother = ( Y - 5 ).
According to the question,
Y - 5 = 7 ( X - 5 )
Y - 5 = 7X - 35
7X - Y = 35 - 5
7X - Y = 30 ----_-----(1)
Five years hence age of daughter = ( X + 5 ).
Five years hence age of mother = ( Y + 5 ).
According to the question,
Y + 5 = 3 ( X + 5 )
Y + 5 = 3X + 15
3X - Y = 5 - 15
3X - Y = -10 -----------(2)
From equation (1) , we get
7X - Y = 30
Y = ( 7X - 30 ) --------(3)
Putting the value of X in equation (2) ,
3X - Y = -10
3X - ( 7X - 30 ) = -10
3X - 7X + 30 = -10
-4X = -10 - 30
-4X = -40
X = 10
Putting the value of X in equation (3) ,
Y = ( 7X - 30 ) = ( 7 × 10 - 30 )
Y = 70 - 30 = 40 years.
Hence,
Present age of daughter = X = 10 year's.
and,
Present age of mother = Y = 40 years
coolpriyanshu:
cab you solve in one variable please
Answered by
13
нєуα
нєяє ιѕ тнє αиѕωєя
ℓєт тнє мσтнєя'ѕ αи∂ ∂αυgнтєя'ѕ αgє вє χ αи∂ у уяѕ яєѕρє¢тινєℓу.
fινє уяѕ αgσ,
мσтнєя'ѕ αgє = (χ - 5) уяѕ
∂αυgнтєя'ѕ αgє = (у - 5) уяѕ
єqυαтισи fσямє∂ α/q :-
(χ - 5) = 7(у - 5)
σи ѕσℓνιиg fυятнєя, ωє gєт
χ - 5 = 7у - 35
χ - 7у = -35 + 5
χ - 7у = -30
αfтєя 5 уяѕ,
мσтнєя'ѕ αgє = (χ + 5) уяѕ
∂αυgнтєя'ѕ αgє = (у + 5) уяѕ
єqυαтισи fσямє∂ α/q :-
(χ + 5) = 3(у + 5)
χ + 5 = 3у + 15
χ - 3у = 15 - 5
χ - 3у = 10
иσω, ωє нανє тωσ єqυαтισиѕ,
χ - 7у = -30
αи∂
χ - 3у = 10
ѕυвтяα¢т вσтн тнє єqυαтισиѕ, ωє gєт
-4у = -40
у = 10
ρυт тнιѕ ιи 1ѕт єqυαтισи
χ - 7(10) = -30
χ - 70 = -30
χ = 40
нєи¢є,
мσтнєя'ѕ αgє = 40 уяѕ
∂αυgнтєя'ѕ αgє = 10 уяѕ
нσρє тнιѕ нєℓρѕ.
нєяє ιѕ тнє αиѕωєя
ℓєт тнє мσтнєя'ѕ αи∂ ∂αυgнтєя'ѕ αgє вє χ αи∂ у уяѕ яєѕρє¢тινєℓу.
fινє уяѕ αgσ,
мσтнєя'ѕ αgє = (χ - 5) уяѕ
∂αυgнтєя'ѕ αgє = (у - 5) уяѕ
єqυαтισи fσямє∂ α/q :-
(χ - 5) = 7(у - 5)
σи ѕσℓνιиg fυятнєя, ωє gєт
χ - 5 = 7у - 35
χ - 7у = -35 + 5
χ - 7у = -30
αfтєя 5 уяѕ,
мσтнєя'ѕ αgє = (χ + 5) уяѕ
∂αυgнтєя'ѕ αgє = (у + 5) уяѕ
єqυαтισи fσямє∂ α/q :-
(χ + 5) = 3(у + 5)
χ + 5 = 3у + 15
χ - 3у = 15 - 5
χ - 3у = 10
иσω, ωє нανє тωσ єqυαтισиѕ,
χ - 7у = -30
αи∂
χ - 3у = 10
ѕυвтяα¢т вσтн тнє єqυαтισиѕ, ωє gєт
-4у = -40
у = 10
ρυт тнιѕ ιи 1ѕт єqυαтισи
χ - 7(10) = -30
χ - 70 = -30
χ = 40
нєи¢є,
мσтнєя'ѕ αgє = 40 уяѕ
∂αυgнтєя'ѕ αgє = 10 уяѕ
нσρє тнιѕ нєℓρѕ.
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