The given equation is
[tex]12.5=2.5x[/tex]We just have to divide by 2.5 each side
[tex]\begin{gathered} \frac{12.5}{2.5}=\frac{2.5x}{2.5} \\ x=5 \end{gathered}[/tex]The solution is 5.
The second equation is
[tex]-10=-8+x[/tex]We have to sum 8 on each side
[tex]\begin{gathered} -10+8=-8+x+8 \\ -2=x \\ x=-2 \end{gathered}[/tex]The solution is -2.
The third equation is
[tex]-10=-2.5x[/tex]We have to divide the equation by -2.5
[tex]\begin{gathered} \frac{-10}{-2.5}=\frac{-2.5x}{-2.5} \\ x=4 \end{gathered}[/tex]The solution is 4.