We have the following:
[tex]6(hx+5)+4=-4(8-18x)+66[/tex]
A system of linear equations has infinite solutions when the graphs are exactly the same line.
for this to happen, on both sides the value of x must be equal:
[tex]\begin{gathered} 6\cdot h=4\cdot18 \\ h=4\cdot\frac{18}{6} \\ h=12 \end{gathered}[/tex]
replacing:
[tex]\begin{gathered} 6\cdot(12x+5)+4=-4\cdot(8-18x)+66 \\ 72x+30+4=-32+72x+66 \\ 7x+34=7x+34 \\ 0=0 \\ \text{true for all x} \end{gathered}[/tex]
