(x + 1) + (x + 4) + (x + 7) + (x + 10) +...+ (x + 28) = 155, (x+1)+(x+4) + (x + 7) + (x+10)+...+(x+28)=155, (x + 1) + (x + 4) + (x + 7) + (x + 10) + . . . + (x + 28) = 155