Explanation:
priorities of operations :
1. brackets
2. exponents
3. multiplications and divisions
4. additions and subtractions
[(18 + 3×2) + 8 + 5×3] + 6
18 + 3×2 = 18 + 6 = 24
24 + 8 + 5×3 = 24 + 8 + 15 = 47
47 + 6 = 53
[(18 + 3×2) + 8 + 5×3] + 6 =
= 18 + 6 + 8 + 15 + 6 = 53