Answer
$(3,-7)$
Work Step by Step
Alphabetical order: s on the horizontal axis, t on the vertical.
Graphing $t+2s=-1$
Set $t=-1 \Rightarrow s=0 \qquad $... $(0,-1)$
Set $t=3 \Rightarrow s=-2 \qquad $... $(-2,3)$
Graphing $s=t+10$
Set $s=6 \Rightarrow t=-4 \qquad $... $(6,-4)$
Set $s=5 \Rightarrow t=-5 \qquad $... $(5,-5)$
Graphically solving: $s=3,\ t=-7$.
Checking:$\qquad \left\{\begin{array}{lll}
-7+2(3) =-1 & & \\
& & \\
3=-7+10 & &
\end{array}\right.$
both equations are satisfied, $(3,-7)$ is the solution.