1)12+18-8=22
2)18-8+12=22
3)12-8+18=22
3 * х = 57
x = 19
х ÷ 68 = 4
x = 272
540 ÷ х = 90
540 = 90x
90x = 540
x = 540 ÷ 90
x = 6
18 230+45 630=63 860:2=31 930