1. 18 - [(15 - 9] - 2
2. 6²-[3²+(3+12) ]
3. 21-[ (2 x 4) + 2 +5]
4. [ (17 - 10) + 4] + 5²
5. 36 ÷ 6 + [ ( 5 x 3) + (13 - 6) + 10]
