`5/14 + -5/7 + -20/41 + 8/13 + -21/41`
`= ( 5/14 + -5/7 ) + ( -20/41 + -21/41 ) + 8/13`
`= ( 5/14 + -10/14 ) + ( -1 ) + 8/13`
`= -5/14 + ( -1 ) + 8/13`
`= -65/182 + -182/182 + 112/182`
`= -65/182 -182/182 + 112/182`
`= -239/182`
`HỌC` `TỐT` `NHA` `!`
`#NOCOPY`