Question

My sister is 3 times as old as I am. Five years from now, she will be twice as old as I will be. How many years old is my sister now?

Answer 1

Let your age be x ∴ your sister's age be 3x

Five years from now,

Your's age = x + 5 and your sister's age = 3x + 5

ATQ

3x + 5 = 2(x + 5)

3x + 5 = 2x + 10

x = 5

Hence your sister's present age is 15 years

Answer 2

My age. sis age
if I consider.
my age
1. 3
2. 6
3. 9
4. 12
5. 15

so sister's age will be 15