My sister was born in 2 years before me. In 2041, she will be twice what my current age is.

Question

My sister was born in 2 years before me. In 2041, she will be twice what my current age is.

Answer 1

s = m + 2

s + 23 = 2m

 

We can either substitute m + 2 for s in the 2nd equation...

 

m + 2 + 23 = 2m

m = 25

 

s = 25 + 2

s = 27

 

Or, we can solve the 2nd equation for s.

 

s = 2m - 23

 

If s = m + 2 and 2m - 23, they equal each other.

 

m + 2 = 2m - 23

m = 25

 

s = 25 + 2

s = 27

 

I am 25 and my sister is 27.