`**` Đáp án `: 1/72 .`
`**` Giải thích `:`
`A = 1/3 - 3/4 - ( - 3/5 ) + 1/72 - 2/9 - 1/36 + 1/15`
`A = [ 1/3 - ( - 3 )/5 + 1/15 ] - [ 3/4 + 2/9 + 1/36 ] + 1/72`
`A = [ 5/15 - ( - 9 )/15 + 1/15 ] - [ 27/36 + 8/36 + 1/36 ] + 1/72`
`A = [ 14/15 + 1/15 ] - [ 35/36 + 1/36 ] + 1/72`
`A = 1 - 1 + 1/72`
`A = 1/72`