Răspuns:
Explicație pas cu pas:
a + 660 + 1291 - 233 + 2 = 1730
a + 1720 = 1730
a = 1730 - 1720 = 10
a+12×55+1291-233+1×2=1730
a+660+1291-233+2=1730
a+660+1291-233=1730-2
a+660+1291-233=1728
a+660+1291=1728+233
a+660+1291=1961
a+660=1961-1291
a+660=670
a=670-660
a=10