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 my age be 'x'

my sister's age = 3x

FIVE YEARS FROM NOW

my age = x+5

my sister's age = 3x+5

according to the conditions

(x+5)*2 = 3x+5

2x+10 = 3x+5

3x+5 = 2x+10

3x-2x = 10-5

x = 5

∴ My sister's age = 3x = 3*5 = 15 years

Answer 2

let I be x
then my sister=3x
5years later=myself=5+x
my sister=3x+5
so by question,2(x+5)=3x+5
2x+10=3x+5
10-5=3x-2x
5=x
so sisters age= 15