= 4/5×7/8+7/8×1/5 = (1-2/5)÷3/5
= 7/8×(4/5+1/5) = 3/5÷3/5
= 7/8×1 = 1
= 7/8
(5) 1-5/8÷25/28-3/10 (6) [5/6-(1/2-1/3)]÷4/9
= 1-7/10-3/10 = [5/6-1/6]÷4/9
= 1-(7/10+3/10) = 2/3×9/4
= 1-1 = 3/2
= 0
5: 9×1/4+1/2
= 9/4+1/2
= 11/4(米)
答:两次一共用去11/4米。
6: 70×(1-13/35)
= 70×22/35
= 44(枚)
答:银牌和铜牌一共有44枚。
7: 1800×1/3-1800×2/9
= 600-400
= 200(吨)
答:第二天比第一天多运走200吨。
8:
(2600-200)÷(1+5)
= 2400÷6
= 400(毫升)
400+200=600(毫升)
答:每个小瓶装药水400毫升,每个大瓶装药水600毫升。