Đáp án+Giải thích các bước giải:

 `1)56+29xx(27-3 xx x)=143`

`29xx(27-3xx x)=143-56`

`29xx(27-3xx x)=87`

`27-3xx x=87:29`

`27-3xx x=3`

`3xx x=27-3`

`3xx x=24`

`x=24:3`

`x=8`

Vậy `x=8`

`2)(64+x xx43):5-27=3`

`(64+x xx43):5=3+27`

`(64+x xx43):5=30`

`64+x xx43=30xx5`

`64+x xx43=150`

`x xx43=150-64`

`x xx43=86`

`x=86:43`

`x=2`

Vậy `x=2`

`3)(71+2xx x).(94:47)=186`

`(71+2xx x).2=186`

`71+2xx x=186:2`

`71+2xx x=93`

`2xx x=93-71`

`2xx x=22`

`x=22:2`

`x=11`

Vậy `x=11`

`4)(67+x xx 5)-(87:3)=93`

`(67+x xx5)-29=93`

`67+x xx5=93+29`

`67+x xx5=122`

`x xx5=122-67`

`x xx5=55`

`x=55:5`

`x=11`

Vậy `x=11`

`5)(4xx x+60:3)-29=19`

`4xx x+(60:3)=19+29`

`4xx x+20=48`

`4xx x=48-20`

`4xx x =28`

`x=28:4`

`x=7`

Vậy `x=7`

`6)(37-12xx x).9=117`

`37-12xx x=117:9`

`37-12xx x=13`

`12xx x=37-13`

`12xx x=24`

`x=24:12`

`x=2`

Vậy `x=2`

`7)130-5xx(67-9xx x)=65`

`5xx(67-9xx x)=130-65`

`5xx(67-9xx x)=65`

`67-9xx x=65:5`

`67-9xx x=13`

`9xx x=67-13`

`9xx x=54`

`x=54:9`

`x=6`

Vậy `x=6`

`8)(67xx x-143)-49=9`

`67xx x-143=9+49`

`67xx x-143=58`

`67xx x=58+143`

`67xx x=201`

`x=201:67`

`x=3`

Vậy `x=3`

`9)(83-x xx 26)-27=60:15`

`(83-x xx26)-27=4`

`83-x xx26=4+27`

`83-x xx26=31`

`x xx26=83-31`

`x xx26=52`

`x=52:26`

`x=2`

Vậy `x=2`

`10)(67+3xx x):2-38=15`

`(67+3xx x):2=15+38`

`(67+3xx x):2=53`

`67+3xx x=53xx2`

`67+3xx x=106`

`3xx x=106-67`

`3xx x=39`

`x=39:3`

`x=13`

Vậy `x=13`

`11)138-5xx(26-3xx x)=98`

`5xx(26-3xx x)=138-98`

`5xx(26-3.x)=40`

`26-3xx x=40:5`

`26-3xx x=8`

`3xx x=26-8`

`3xx x=18`

`x=18:3`

`x=6`

Vậy `x=6`