Răspunsuri

2014-10-23T00:15:03+03:00
S = a1 × n + r ×  \frac{n(n-1)}{2}
S = 100 x 60 + 2 x   \frac{100 x  99}{2}
S = 6000 + 2 x 9900
S = 6000 + 19800
S =25800