Answer :
We have the next equation
[tex]10+15x-30=40[/tex]We sum similar terms
[tex]15x-20=40[/tex]then we clear x
[tex]\begin{gathered} 15x=40+20 \\ 15x=60 \\ x=\frac{60}{15} \\ x=4 \end{gathered}[/tex]the value of x=4
We have the next equation
[tex]10+15x-30=40[/tex]We sum similar terms
[tex]15x-20=40[/tex]then we clear x
[tex]\begin{gathered} 15x=40+20 \\ 15x=60 \\ x=\frac{60}{15} \\ x=4 \end{gathered}[/tex]the value of x=4