T+6.8=9t+10
t+6.8=9t+10 ,
t-9t=10-6.8 ,
-8t=3.2 ,
t=-3.2/8 ,
t=-0.4 .
t+6.8=9t+10
6.8-10=9t-t
8t=-3.2
t=-0.4