32-24+64:8= 8*9-(42-7)= 42:(21-15)=
32-24+64:8 1) 64:8=8 2) 24+8=32 3) 32-32=0 8*9-(42-7) 1) 42-7=35 2) 8*9=72 3) 72-35=37 42:(21-15) 1) 21-15=6 2) 42:6=7
32-24+64:8=32-24+8=16 8*9-(42-7)=72-35=37 42:(21-15)=42:6=7