Răspuns :
Explicație pas cu pas:
1:7=0.14
2:7=0.28
3:7=0.42
4:7=0.57
5:7=0.71
6:7=0.85
7:7=1
8:7=1.14
9:7=1.28
10:7=1.42
11:7=1.57
12:7=1.71
13:7=1.85
14:7=2
15:7=2.14
16:7=2.28
17:7=2.42
18:7=2.57
19:7=2.71
20:7=2.85
toate adunate=29.91
2+4+6+8+10+12+14+16+18+20+22+24+26+28+30+32+34+36+38+40=420