[1减(1\4加3\8)]除1\4

1.0 1/6 + （5/6-3/4）/ (2/5) = 1/6 + (20/24 - 18/24) / (2/5)
= 1/6 + (2/24) / (2/5)
= 1/6 + (2/24 * 5/2)
= 1/6 + 5/24
= 4/24 + 5/24 = 9 / 24 = 3 / 8
2.0 (4/5 * 1/4 ) + (3.2* 1/4) - (1 / 4) = (1/5) + (16/5 * 1/4) - (1/4)
= (1/5) + (4/5) - (1/ 4)
= 1 - (1 / 4)
= 3 / 4
3.0 [1 - (1/4+3/8) ] / (1/4) = [1- (2/8 +3/8)] / (1/4)x05x05x05x05
= [1 - 5/8] / (1/4)x05x05x05x05
= (3/8) / (1/4) = (3/8)* 4 = 3/2x05
4.0 (7/20 - 5/36) * 4 - (4/9) = (7/20 - 5/36) *4 - (4/9)
= (252/720 - 100/720) * 4 - (4/9)
= (152/720) *4 - (4/9)
= 152/180 - (4/9)
= 38/45 - (4/9) = 38/45 - 20/45 = 18/45 = 2/5
5.0 13 / (1/4 + 5/6) * 3/4 = 13 / (6/24 + 20/24) * 3/4x05x05x05x05x05
= 13 / (26/24) * 3/4x05x05x05x05x05
= 13 / (26/32) = 13 * (32/26) = 32/2 = 16

人在。快点啊、