1. The problem statement, all variables and given/known data Derive the formula v= (v'+u)/(1+v'u/c^2) the velcoty addition formula using the below formulas? 2. Relevant equations 1. vt1=L+ut1 2. (proper time)=(proper length)/v'+(proper length)/c 3. ct2=L-ut2 4. (dilated time)= (proper time)/(sqrt(1-v^2/c^2)) 5. L=(proper length)sqrt(1-v^2/c^2) 3. The attempt at a solution Ok so here is what I did I solved equation 1 above for t1 and got t1=(L+ut1)/v and equation 3 for t2 and got t2=(L-ut2)/c. I then added them together to get (dilated time or delta t)=(L+ut1)/v+(L-ut2)/c. Then I used equation 4 to get ((L+ut1)/v+(L-ut2)/c)sqrt(1-v^2/c^2)=(proper time). Then I set that equal ti equation 2 ((L+ut1)/v+(L-ut2)/c)sqrt(1-v^2/c^2)= (proper length)/v'+(proper length)/c. Then (proper length)=L/sqrt(1-v^2/c^2) and this is where I get lost in my algebra I cant seem to get rid of L and (proper length) in order to find the correct formula?