Simple..
you have: 3.4t+19.36=-10.22
You must isolate the variable t to find the answer....
3.4t+19.36=-10.22
-19.36 -19.36
Leaving you with-->>
3.4t=-29.58
Now simply divide....
[tex] \frac{3.4t}{3.4}= \frac{-29.58}{3.4} [/tex]
t=-8.7
Thus, your answer.