The equations are
[tex]\begin{bmatrix}a-3b=-1...........1 \\ 2a+3b=16..........2\end{bmatrix}[/tex]Using Substitution method of simultaneous equation
Isolate for 'a' from equation 1
[tex]a=-1+3b........3[/tex]Therefore,
[tex]\begin{gathered} \mathrm{Substitute\:}a=-1+3b \\ 2\left(-1+3b\right)+3b=16 \\ -2+9b=16 \\ 9b=16+2=18 \\ 9b=18 \\ b=\frac{18}{9}=2 \\ \therefore b=2 \end{gathered}[/tex]Then
[tex]\begin{gathered} \mathrm{For\:}a=-1+3b \\ \mathrm{Substitute\:}b=2 \\ a=-1+3\cdot\:2=-1+6=5 \\ \therefore a=5 \end{gathered}[/tex]Hence, the answer is
[tex](a,b)=(5,2)[/tex]