1. The problem statement, all variables and given/known data It takes light 40 years to get from planet 1 to planet 2 anna who was just born leves planet 1 to go to planet 2. can she make it to planet 2 in 30 years? 2. Relevant equations L=Lo/Yv V=Dist/Time Yv=1/(1-V^2/c^2)^(1/2) 3. The attempt at a solution I know the anwser is yesand if anna moves at .8c she would make it in 30 years but i need help understanding why. in my book it says to take V=40LY/30Y and i get that part but then it says to devide both sides by c and it gets V/C=(40LY/30Y)((1-V^2/c^2)^(1/2)) i want to know WHY you have to devide one side by c tha the other side by 1/(c(1-V^2/c^2)^(1/2)) after that step i understand it but that step is confusing me.