[tex]\bf \begin{array}{lllll}
solutions&graphs&slopes\\
----&----&----\\
\textit{exactly one}&
\begin{array}{llll}
\textit{the two lines intersect}\\
\textit{at one point}
\end{array}&\textit{different slopes}\\\\
infinitely\quad many&
\begin{array}{llll}
\textit{the two lines coincide}\\
\textit{one is right on top}\\
\textit{ of the other}
\end{array}&
\begin{array}{llll}
\textit{equal slopes}\\
\textit{equal y-intercepts}
\end{array}
\end{array}[/tex]
[tex]\bf \textit{no solution}\qquad\quad &\textit{lines are parallel} \qquad &
\begin{array}{llll}
\textit{equal slopes}\\
\textit{different y-intercepts}
\end{array}
\end{array}[/tex]
for example, let's look at the first set
y+3x =5 or y = -3x+ 5
and y = -3x + 2
y = m + b
the slopes are equal, the y-intercepts differ
that means, they're just parallel lines, no solution