1.21–3×2+56
=21–6+56
=15+56
=71
2.15÷3+16÷4
=5+16÷4
=5+4
=9
3.63÷(3+4)×2+4×8
=63÷7×2+4×8
=9×2+4×8
=18+4×8
=18+32
=50