afla termenul necunoscut
a-(6×7)=48..........1219-a=948
(8×7)-a=20..........a-4914=1748
a+(8:1)=24...........1219-a=999
(7×7)+a=21..........(6×6):a=4
a-(10:10)=99.......a:(4:1)=7​