Question

(x+1)+(x+4)+(x+7).............+(x+8)=195

Answer 1

\(\left(x+1\right)+\left(x+4\right)+\left(x+7\right)+...+\left(x+28\right)=195\)

\(\Leftrightarrow\left(x+x+...+x\right)+\left(1+4+...+28\right)=195\)

\(\Leftrightarrow10x+145=195\)

\(\Leftrightarrow10x=50\Leftrightarrow x=5\)