Question 260542
u - 1.96t = 10 --(1)
u + 1.96t = 30  --(2)
Add (1)+ (2) ==> 2u=40
                   u=40/2
                   u=20
Put u value into (1) ==> 20-1.96t=10
                           -1.96t=10-20
                            -1.96t=-10
                             1.96t=10
                                 t=10/1.96
                                 t=5.102
Therefore, u=20 and t=5.102