Respuesta :

C is the correct answer

x+20+10x = 20+9x
11x+20 = 20+9x
11x-9x = 20-20
2x = 0
x = 0
X = 0

Why? Because you collect like terms

So x+20+10x=20+9x becomes x+10x=9x

Then once again you add the like terms and it becomes 11x=9x

Then you collect the like terms and divide both sides by two and get zero