Explanation
[tex]\begin{gathered} 3x-2y=17\Rightarrow equation(1) \\ 5x+10y=-25\Rightarrow equation(2) \end{gathered}[/tex]Step 1
a) isolate x in equation (1) and substitute in equation (2)
so
[tex]\begin{gathered} 3x-2y=17\Rightarrow equation(1) \\ \text{add 2y in both sides} \\ 3x-2y+2y=17+2y \\ 3x=17+2y \\ \text{divide both sides by 3} \\ \frac{3x}{3}=\frac{17+2y}{3} \\ x=\frac{17+2y}{3} \end{gathered}[/tex]replace in equation(2)
[tex]\begin{gathered} 3x-2y=17\Rightarrow equation(1) \\ 5x+10y=-25\Rightarrow equation(2) \end{gathered}[/tex]