Question 569689
{{{x+3x+6x-20=180}}}
{{{10x-20=180}}}
{{{10x=200}}}
{{{x=20}}}
x doesnot equal 10
to prove it put 10 in place of x and solve

.
{{{x+3x+6x-20=180}}}
{{{10+30+60-20=180}}}
{{{100-20=180}}}
{{{80=180}}}
incorrect
.
{{{x+3x+6x-20=180}}}
{{{20+60+120-20=180}}}
{{{180=180}}}
correct {{{highlight(x=20)}}}