Answer :
This is one-step equation.
[tex]W+2.1=5.4 \\ W+2.1-2.1=5.4-2.1 \\ W=3.3 \\ CHECK- \\ 3.3+2.1=5.4[/tex]
[tex]W+2.1=5.4 \\ W+2.1-2.1=5.4-2.1 \\ W=3.3 \\ CHECK- \\ 3.3+2.1=5.4[/tex]