$#Đáp án+Giải thích các bước giải:$
$13/$
`1/5 * (-7/3 + 2/8) : 0,25`
`= 1/5 * (-25)/12 : 1/4`
`= -5/12 : 1/4`
`= -5/12 * 4`
`= -5/3`
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$14/$
`1/4 - (13/19 - (-2)/8) + (13/19 - 5/7)`
`= 1/4 - (13/19 + 2/8) + (13/19 - 5/7)`
`= 1/4 - 13/19 - 2/8 + 13/19 - 5/7`
`= (1/4 - 2/8) + (-13/19 + 13/19) - 5/7`
`= 0 + 0 - 5/7`
`= -5/7`
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$15/$
`9/24 + (-8)/(-14) - 12/32`
`= 9/24 + 8/14 - 12/32`
`= 252/672 + 384/672 - 252/672`
`= 384/672`
`=4/7`
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