300 - (90 + 70) + (86 - 46) = 180
1) 90 + 70 = 160
2) 86 - 46 = 40
3) 300 - 160 = 140
4) 140 + 40 = 180
90 : (10 * 9) : (9 : 9) = 1
1) 10 * 9 = 90
2) 9 : 9 = 1
3) 90 : 90 = 1
4) 1 : 1 = 1
0 * 8 + 7 = 7
1) 0 * 8 = 0
2) 0 + 7 = 7
0 * (8 + 7) = 0
1) 8 + 7 = 15
2) 0 * 15 = 0
91 : 13 * 7 = 49
1) 91 : 13 = 7
2) 7 * 7 = 49
84 : (14 * 3) = 2
1) 14 * 3 = 42
2) 84 : 42 = 2