` color{#e6f0ff}{@}color{#c7ddff}{Sp}color{#99c2ff}{i}color{#66a3ff}{di}color{#3385ff}{e}color{#0066ff}{rC}color{#0044cc}{o}color{#002d80}{ol}color{#001b4d}{er}color{#000a1a}{@} `

Bài ` 16 : `

` a) ( 7 - 1 / 5 + 1 / 3 ) - ( 6 + 9 / 5 + 4 / 3 ) `

` = 7 - 1 / 5 + 1 / 3 - 6 - 9 / 5 - 4 / 3 `

` = ( 7 - 6 ) - ( 1 / 5 + 9 / 5 ) + ( 1 / 3 - 4 / 3 ) `

` = 1 - 2 + ( - 1 ) = - 2 `

` b) 7 + ( 7 / 12 - 1 / 2 + 3 ) - ( 1 / 12 + 5 ) `

` = 7 + 7 / 12 - 1 / 2 + 3 - 1 / 12 - 5 `

` = ( 7 + 3 - 5 ) + ( 7 / 12 - 6 / 12 - 1 / 12 ) `

` = 5 `

` c) ( 3 - 1 / 4 + 2 / 3 ) - ( 5 - 1 / 3 - 6 / 5 ) - ( 6  - 7 / 4 + 3 / 2 ) `

` = 3 - 1 / 4 + 2 / 3 - 5 + 1 / 3 + 6 / 5 - 6 + 7 / 4 - 3 / 2 `

` = ( 3 - 5 - 6 ) - ( 1 / 4 - 7 / 4 + 6 / 4 ) + ( 2 / 3 + 1 / 3 ) + 6 / 5 `

` = - 8 + 1 + 6 / 5 = - 5 , 8 `

` d) ( 6 - 2 / 3 + 1 / 2 ) - ( 5 + 5 / 3 - 3 / 2  ) - ( 3 - 7 / 3 + 5 / 2 ) `

` = 6 - 2 / 3 + 1 / 2 - 5 - 5 / 3 + 3 / 2 - 3 + 7 / 3 - 5 / 2 `

` = ( 6 - 5  - 3 ) - ( 2 / 3 + 5 / 3 - 7 / 3 ) + ( 1 / 2 + 3 / 2 - 5 / 2 ) `

` = - 2 - 1 / 2 = - 2 , 5 `

Bài ` 17 : `

` a) 2 / 5 * 3 / 8 + 5 / 8 * 2 / 5 = 2 / 5 * ( 3 / 8 + 5 / 8 ) = 2 / 5 * 1 = 2 / 5 `

` b) 2 / 3 * 5 / 2 - 3 / 4 * 2 / 3 = 2 / 3 * ( 10 / 4 - 3 / 4 ) = 2 / 3 * 7 / 4 = 7 / 6 `

` c) 5 / 7 * 19 / 23 - 12 / 23 * 5 / 7 = 5 / 7 * ( 19 / 23 - 12 / 23 ) = 5 / 7 * 7 / 23 = 5 / 23 `

` d) ( - 2 ) / 3 * 3 / 11 + ( - 16 ) / 9 * 3 / 11 = 3 / 11 * ( - 6 / 9 - 16 / 9 ) = 3 / 11 * ( - 22 / 9 ) = - 2 / 3 `

` e) ( - 5 ) / 9 * 3 / 11 + ( - 13 ) / 18 * 3 / 11 = 3 / 11 * ( -  10 / 18 - 13 / 18 ) = 3 / 11 * ( - 23 / 18 ) = - 23 / 66 `

` f) 2 / 13 * ( - 5 ) / 3 + 11 / 13 * ( - 5 ) / 3 = - 5 / 3 * ( 2 / 13 + 11 / 13 ) = - 5 / 3 * 1 = - 5 / 3 `