Respuesta :

the equation is
20+a=18

subtract 20 from both sides using additive property that leaves you with

a= -2
Salutations!

Let the number be [tex]x[/tex]

The equation would be: [tex]x+20=18[/tex]

Lets solve this!

We need to always keep the variables aside, and the numbers aside.

[tex]x=20-18[/tex]

[tex]x=2[/tex]

Hope I helped (:

Have a great day!