Question

X+(X+1)+....+(X+30)=620

Answer 1

[tex]S =x+(x+1)+(x+2)+...+(x+30)\\ S=x *31+1+2+...+30\\ S=31x+ \frac{30*31}{2}=465+31x \\ 465+31x=620\\ 31x=155\\ x=5[/tex]

Answer 2

31x+(30×31)÷2=
31x+930÷2=
31x+465=620
31x=115
x=5