s il vous plait aider moi ex 21

M=7-[12-(9-1)]
M=7-[12-8]
M=7-4
M=3

N=3x[2+(5+7):3]
N=3x[2+12:3]
N=3x[2+4]
N=3x6
N= 18

P=[5:(7+3)]x6
P= [5:10]x6
P=0,5x6
P=3

O=13-[2+7-(8-2):2]
O=13-[2+7-6:2]
O=13-[2+7-3]
O=13-[9-3]
O=13-6
O=7