Asked by Peter madison
John is eight year older than his sister.In three years,he will be as twice as she will be then.
How old are they both now?
How old are they both now?
Answers
Answered by
Bosnian
J = John present age
S = sister present age
J = S + 8
After 3 years John wil be J + 3 yrs old.
Sister wil be S + 3 yrs old.
In three years,he will be as twice as she will be then mean:
( J + 3 ) / ( S + 3 ) = 2
In this equation replace J with S + 8
( S + 8 + 3 ) / ( S + 3 ) = 2
( S + 11 ) / ( S + 3 ) = 2
Multiply both sides by S + 3
S + 11 = 2 ( S + 3 )
S + 11 = 2 S + 6
Subtract 6 to both sides
S + 11 - 6 = 2 S + 6 - 6
S + 5 = 2 S
Subtract S to both sides
S + 5 - S = 2 S - S
5 = S
S = 5
J = S + 8 = 5 + 8 = 13
John is 13 yrs old, sister is 5 yrs old.
Proof:
After 3 years John wil be 13 + 3 = 16 yrs old
Sister wil be 5 + 3 = 8 yrs old
16 / 8 = 2
S = sister present age
J = S + 8
After 3 years John wil be J + 3 yrs old.
Sister wil be S + 3 yrs old.
In three years,he will be as twice as she will be then mean:
( J + 3 ) / ( S + 3 ) = 2
In this equation replace J with S + 8
( S + 8 + 3 ) / ( S + 3 ) = 2
( S + 11 ) / ( S + 3 ) = 2
Multiply both sides by S + 3
S + 11 = 2 ( S + 3 )
S + 11 = 2 S + 6
Subtract 6 to both sides
S + 11 - 6 = 2 S + 6 - 6
S + 5 = 2 S
Subtract S to both sides
S + 5 - S = 2 S - S
5 = S
S = 5
J = S + 8 = 5 + 8 = 13
John is 13 yrs old, sister is 5 yrs old.
Proof:
After 3 years John wil be 13 + 3 = 16 yrs old
Sister wil be 5 + 3 = 8 yrs old
16 / 8 = 2
Answered by
Henry
Sister: X yrs. old.
John: x + 8 yrs. old.
3 yrs. later:
Sister: x + 3.
John: (x+8) + 3 = x + 11.
x + 11 = 2(x + 3),
X = 5.
x + 8 = 5 + 8 = 13.
John: x + 8 yrs. old.
3 yrs. later:
Sister: x + 3.
John: (x+8) + 3 = x + 11.
x + 11 = 2(x + 3),
X = 5.
x + 8 = 5 + 8 = 13.
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