Question

x+(x+1)+(x+2)+...+(x+30)=1240

Answer 1

X+(X+1)+(X+2)+...+(X+30)=1240

=(X+X+...+X)+(1+2+...+30)=1240 (31 so X)

=31X+465=1240

=31X=775

=X=25

Answer 2

x+(x+1)+(x+2)+.........+(x+30)=1240

x\(\times\)31+1+2+3+.......+30=1240

x\(\times\)31+465=1240

x\(\times\)31=775

x=775:31

x=25

Vậy số cần tìm là 25