Given the equation
[tex]x-20=17[/tex]To determine the value of x you have to pass the term "-20" to the right side of the equal sign, for this, you have to apply the opposite operation to both sides of it. If "-20" is subtracting, the opposite operation is to add 20, so that:
[tex]\begin{gathered} x-20+20=17+20 \\ x=37 \end{gathered}[/tex]And we determined that the value of x is 37
