`a) 2/3 - 5/7 . 14/25`
`= 2/3 - (5.14)/(7.25)`
`= 2/3 - (1.2)/(1.5)`
`= 2/3 - 2/5`
`= 4/15`
`b) (-5)/8 . 5/7 - 3/7 : 8/5 + 2/7`
`= 5/8 . (-5)/7 - 3/7 . 5/8 + 2/7`
`= 5/8 . ((-5)/7 - 3/7) + 2/7`
`= 5/8 . (-8)/7 + 2/7`
`= (5(-8))/(8.7) + 2/7`
`= (5(-1))/(1.7) + 2/7`
`= (-5)/7 + 2/7 `
`= (-3)/7`
`c) 75% + 1,1 : (2/5 - 1 1/2) - ((-1)/2)^2`
`= 3/4 + 11/10 : (2/5 - 3/2) - 1/4`
`= 3/4 + 11/10 : (-11/10) - 1/4`
`= 3/4 + 11/10 . (-10/11) - 1/4`
`= 3/4 + (-1) - 1/4`
`= -1/2`
(Chúc bạn học tốt)
