Question

$-$x + 2y = 0; 10x + 15y = 105

Answer 1

$$\begin{gathered} \left(\mathrm{ii}\right)-x+2y=0...\left(1\right) \\ 10x+15y=105...\left(2\right) \\ x=2y...\left(3\right)\left(\mathrm{From}\mathrm{eq}1\right) \\ \mathrm{Substituting}\mathrm{the}\mathrm{value}\mathrm{of}x\mathrm{in}\mathrm{eq}\left(2\right),weget: \\ 10\left(2y\right)+15y=105 \\ \Rightarrow 20y+15y=105 \\ \Rightarrow 35y=105 \\ \Rightarrow y=3 \\ \mathrm{Substituting}\mathrm{the}\mathrm{value}\mathrm{of}y\mathrm{in}\mathrm{eq}\left(3\right),weget: \\ x=2\times 3 \\ \Rightarrow x=6 \\ \therefore x=6,y=3\mathrm{is}\mathrm{the}\mathrm{solution}. \end{gathered}$$