(3) 4/5×7/8+7/8÷5 (4) (1-8/15x3/4)÷3/5 = 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 = 05: 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 |