Answer :

naǫ
[tex]5x+ay=2 \\ bx+3y=8[/tex]

Write it in the y=mx+b form.

[tex]ay=-5x+2 \\ 3y=-bx+8 \\ \\ y=-\frac{5}{a}x+\frac{2}{a} \\ y=-\frac{b}{3}x+\frac{8}{3}[/tex]

The system will be inconsistent when the equations describe two parallel lines.
Two lines are parallel when their slopes are identical.
[tex]-\frac{5}{a}=-\frac{b}{3} \\ ab=(-5) \times (-3) \\ ab=15[/tex]

Also they can't be the same line, so the y-intercepts must be different.
[tex]\frac{2}{a} \not= \frac{8}{3} \\ 8a \not= 2 \times 3 \\ 8a \not= 6 \\ a \not= \frac{6}{8} \\ a \not= \frac{3}{4}[/tex]

So for every value of a and b such that ab=15 and a≠3/2 this system of equations is inconsisent.

It can be:
[tex]5x+5y=2 \\ 3x+3y=8 [/tex]
or
[tex]5x+15y=2 \\ x+3y=8[/tex]
or
[tex]5x+\frac{1}{2}y=2 \\ 30x+3y=8[/tex]
etc.