(x+1)+(x+2)+...(x+41)=40x+860
Se desfac parantezele si grupam termenii, in membrul stang al egalitatii.
Obtinem:
41X+ (1+39)+(2+38)....+(15+25) +40+41=40X+860
41X+15 x 40 +40 +41 =40X +860
41X+681=40X+860 | -40X
41X-40X+681=40X-40X+860
X+681=860
X=860-681
X=179