N+(n+1)+(n+2)=81
3n+3=81
3n=78
n=26
Произведение
26·27·28=19656
Ответ. б)
17*31+17*11-42*37=(17*31+17*11)-42*37=(17*(31+11))-42*37=17*42-42*37=42* (17-37)=42* (-20)=-840
<span>3 3 3 3 3 = 72 3 3 3 3 3 = 336 33-33 :3 = 22 (3 3 +3 3)* 3 = 198 3 3 3 3 3 = 243 (3 -3) *(33- 3) = 0</span>
A(7+7 * 3)
7 *3=14
14 +7=21a
49*23+3920/28= 1127+140 = 1167