01-1 Simultaneous Equations: sub always works

Question 1:
Solve the simultaneous equations: 

$ \begin{align}
   2x-y+3&=0 \\
 xy+y&=15 
\end{align}$ 

Question 2:

Solve the simultaneous equations: 

$ \begin{align}
   y-{{x}^{2}}&=12-4x \\
  y-3x&=2
\end{align}$

Question 3:

Solve the simultaneous equations: 

$ \begin{align}
   2y&=x+3 \\
  2{{x}^{2}}+2{{y}^{2}}-x+y&=11 
\end{align}$

Question 4:

Solve the simultaneous equations: 

$ \begin{align}
  & x+2y-3=0 \\
 & {{x}^{2}}+xy-2{{y}^{2}}=1 
\end{align}$

Question 5:

Solve the simultaneous equations:

$\begin{align}
  & 2x+y=3 \\
 & {{x}^{2}}+{{y}^{2}}=5 
\end{align}$

Question 6:

Solve the simultaneous equations:

$ \begin{align}
  & y=x+2 \\
 & 2{{x}^{2}}+{{y}^{2}}-5xy=8
\end{align}$

Question 7:

Solve the simultaneous equations:

$ \begin{align}
  & y=2x+1 \\
 & {{x}^{2}}+y-7x+5=0
\end{align}$

Question 8:

Solve the simultaneous equations:

$ \begin{align}
  & 3xy-5x=2 \\
 & 3x+y=8
\end{align}$

Question 9:

Solve the simultaneous equations:

$ \begin{align}
  & 2x+5y=6 \\
 & 4{{x}^{2}}+16{{y}^{2}}=20x+4y-19
\end{align}$

Question 10:

Solve the simultaneous equations:

$ \begin{align}
  & 2y=3x-7 \\
 & 2{{x}^{2}}-2xy+{{y}^{2}}=13
\end{align}$

Question 11:

Solve the simultaneous equations:

$ \begin{align}
  & 2x=3y-3 \\
 & 9{{y}^{2}}-5{{x}^{2}}=10x+6
\end{align}$

Question 12:

Solve the simultaneous equations:

$ \displaystyle \begin{align}
  & 5x+3y+7\text{ }=0 \\
 & 3{{y}^{2}}={{x}^{2}}-4y+3
\end{align}$