Both are linear.
Linear function equation : y=mx+c
You can show the first equation like this = [tex]y=0\cdot x+(-10.2)[/tex]
As you can see it is a linear function. Only, x's coefficent is 0.
The second one : [tex]3x+5y=15\\ \\ 5y=15-3x\\ \\ y=\frac { 15-3x }{ 5 } =\quad y=\frac { -3x+15 }{ 5 } [/tex]
As you can see it is also a linear function.