Math problem about age
Arvind is eight year older than his sister. in three year, he will be twice as old as his sister. how old was they are now?
Let x be a Arvind's age.
Let x - 8 be his sister's age.
In 3 years, Arvind's age will be x + 3
In 3 years, the sister's age will be x - 8 + 3 = x - 5
In 3 years, Arvind is twice as old as his sister.
x + 3 = 2 × (x - 5)
x + 3 = 2x - 10
2x - 10 = x + 3
Subtract x from both sides.
2x - x - 10 = x - x + 3
2x - x - 10 = 3
Add 10 to both sides
2x - x - 10 + 10 = 3 + 10
2x - x = 3 + 10
x = 13
Arvind's age is 13
His sister's age is 13 - 8 = 5.
In 3 years, Arvind's will be 16 and the sister will be 8.
16 is twice as big as 8.
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