Teddy has two sisters. One of them is 3 years younger than Teddy, the other one is 7 years younger than her only brother. How old was the older sisters when the younger sister was born?

Given:

Teddy has two sisters. One of them is 3 years younger than Teddy, the other one is 7 years younger than her only brother.

To find:

The age of older sister at the time when the younger sister was born.

Solution:

Let the age of Teddy be x.

One sister is 3 years younger than Teddy.

Age of one sister = x-3 years

The other one is 7 years younger than her only brother. It means other sister is 7 years younger than Teddy.

Age of other sister = x-7 years

Clearly (x-3) > (x-7). So, difference between the ages of sisters is

Therefore, the age of older sister is 4 years when the younger sister was born.

step-by-step explanation:

he spend 5.1 minutes chatting with his friends.

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5.1