Answer
Infinitely many solutions.
Work Step by Step
To solve a pair of equations in two variables graphically, first put each equation in function form, $y=f(x)$.
1. Graph the equations on a common screen.
2. Find the points of intersection of the graphs.
The solutions are the x- and y-coordinates of the points of intersection.
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$\begin{array}{ll}
12x+15y=-18\ \ /-12x & 2x+\frac{5}{2}y=-3\ \ /\times 2\\
15y=-12x-18\ \ /\div 15 & 4x+5y=-6\ \ /-4x\\
y=-\frac{4}{5}x-\frac{6}{5} & 5y=-4x-6\ \ /\div 5\\
& y= -\frac{4}{5}x-\frac{6}{5}
\end{array}$
1. No need to graph, since...
2. ...the two equations have the same graph.
There are
infinitely many solutions.
(see below for the graphs)
