"In 2010, a 20-year-old astronaut leaves her twin on Earth and goes on a rocket to explore the galaxy. The rocket moves at 2.7 x 10^8 m/s during the voyage. It returns to earth in the year 2040. Using relativity, calculate the age of the returning astronaut."
Δtm = Δts / √(1-((v^2)/(c^2)))
The Attempt at a Solution
It is a simple calculation, but I am having trouble knowing where to plug in the 30 years of time passed on earth. Subscript "s" is supposed to represent time passed with the observer at rest with respect to an event, and subscript "m" represents time passed with the observer in motion with respect to the event.