4 ⋅ 2 ⋅ 20 – (5 + 8 – (3 – 8))
10 + 9 ⋅ (20 – 15)
4 ⋅ 20 – (2 – 8 ⋅ 2) + (5 – 7)
21 – 3 + – 9 = – 3 + 21 + – 9
5 + – 8 + 3 = 3 + – 8 + 5
1 ⋅ (20 – 15) – 15
– 3 + 4 = 4 – 3
54 + 2 – 7 = – 7 + 54 + 2
– 4 + – 5 – 1 = – 5 – 1 – 4
24 ⋅ (20 + 2) – 15 ⋅ (2 + 5) – 7
