Răspuns :
(2+4+6+8+...+100)+(7+14+...+70)
[2×(1+2+3+4+...+50]+[7×(1+2+...10)]
[2×(50×51)]:2+[7×(10×11:2)]
50×51 + 7×45
2550+315=2865
[2×(1+2+3+4+...+50]+[7×(1+2+...10)]
[2×(50×51)]:2+[7×(10×11:2)]
50×51 + 7×45
2550+315=2865