`b)`
`(-5)/(4) + 1/6 : 1/2`
`=> (-5)/(4) + 1/6 . 2/1 `
`=> (-5)/(4) + 2/6 `
`=> (-5)/(4) + 1/3`
`=> (-15 + 4)/12`
`=> (-11)/(12)`
`c)`
`15/17 . 19/15 - 15/17 . 4/15`
`=> 15/17 . (19/15 - 4/15)`
`=>` `15/17 . 15/15`
`=> 15/17 . 1`
`=> 15/17`
`d)`
`1/3^4 . 39^4/13^4 + \sqrt{25/16} - (1/2)^2`
`=>` `1/81 . (39/13)^4 + 5/4 - 1/4`
`=>` `1/81 . (39/13)^4 + 1`
`=>` `1/81 . 2313441/28561 + 1`
`=>` `2313441/2313441 + 1`
`=> 1 + 1`
`=> 2`
`\text{@Sứa}`
`\text{Chúc bạn học tốt ^^ }`
