Question 3822
We can represent this algabrecially

1) Put the problem in a algabracic form
2) Solve
3) Check

Work
1) {{{x+x+1+x+2=18}}}
1a){{{3x+3=18}}}
2) {{{3x+3-3=18-3}}}
2a){{{3x=15}}}
2b){{{3x/3=15/3}}}
2c){{{x=5}}}
3) {{{5+6+7=18}}}
3a){{{18=18}}}