Let's try to solve the system:
Taking the first equation and solving for x, we get:
[tex]\begin{gathered} 10x+9y=25 \\ 10x=25-9y \\ x=\frac{25-9y}{10} \\ x=2.5-0.9y \end{gathered}[/tex]Replacing it on the second and solving for y, we get:
[tex]\begin{gathered} 20x+6y=-10 \\ 20(2.5-0.9y)+6y=-10 \\ 50-18y+6y=-10 \\ 50-12y=-10 \\ -12y=-10-50 \\ -12y=-60 \\ y=\frac{-60}{-12} \\ y=5 \end{gathered}[/tex]Now, we can calculate x, replacing y by 5 as follows:
[tex]\begin{gathered} x=2.5-0.9y \\ x=2.5-0.9(5) \\ x=2.5-4.5 \\ x=-2 \end{gathered}[/tex]It means that x = -2 and y = 5 is the solution for the system.
Answer: The system has one solution and it is x = -2 and y = 5