简便计算题 如下 好的话我把分都给你!

6300÷﹙63×5﹚
=6300/63/5
=100/5
=20
450÷18
=450/9/2
=50/2
=25
840÷5÷8
=840/(5*8)
=840/40
=21
42÷9+48÷9
=42*1/9+48*1/9
=(42+48)*1/9
=90*1/9
=10
150÷5-100÷5
=150*1/5-100*1/5
=(150-100)*1/5
=50*1/5
=10