Đáp án:

Giải thích các bước giải:

 123-3,5×7,5=123-26,25
                     =96,75
1,04:0,5+36,78=2,08+36,78=38,86
14,8×3,6+12,6=53,28+12,26=65,54
(19,8:11)-7,35=1,8-7,35=-5,55
15,6+4,18×3,4=15,6+14,212=29,812
3,58×6,4+56,45=22,912+56,45=79,362
tìm x
12,6×x=123
⇒x=123:12,6
⇒x=205/21
x-3,56=20,4
⇒x=20,4+3,56
⇒x=23,96
x-7,2=5,64

⇒x=5,64+7,2
⇒x=12,84
x+24,18=52,36
⇒x=52,36-24,18
⇒x=28,18
x+46,18=98,4
⇒x=98,4-46,18
⇒x=5,22
18,6-x=5,34
⇒x=18,6-5,34
⇒x=13,26
y:3,4=35,9
⇒y=35,9×3,4
⇒y=39,3
75:y=12
⇒y=12×75
⇒y=900
y×3,9=17,55
⇒y=17,55:3,9
⇒y=4,5
3.
124,34m
22,35m
đánh giá cho mk 5* nha^.^

Tính biểu thức:

+$123-3,5x7,5=123-26,25=96,75$

+$1,04:0,5+36,78=2,08+36,78=38,86$

+$14,8x3,6+12,6=53,28+12,6=65,88$

+$(19,8:11)-7,35=1,8-7,35=-5.55$

+$15,6+4,18x3,4=15,6+14,212=29,812$

+$3,58x6,4+56,45=22,912+56,45=79,362$

Tìm $x$:

+$12,6$x$x=123$

$x=123:12,6$

$x≈9,8$

Vậy $x=9,8$

+$x-3,56=20,4$

$x=20,4+3,56$

$x=23,96$

Vậy$x=23,96$

+$x-7,2=5,64$

$x=5,64+7,2$

$x=12,84$

Vậy$x=12,84$

+$x+24,18=52,36$

$x=52,36-24,18$

$x=28,18$

Vậy$x=28,18$

+$x+46,18=98,4$

$x=98,4-46,18$

$x=52,22$

Vẫy=52,22$

+$18,6-x=5,34$

$x=18,6-5,34$

$x=13,26$

+$y:3,4=35,9$

$y=35,9$x$3,4$

$y=122,06$

Vậy$x=122,06$

+$75:y=12$

$y=75:12$

$y=6,25$

Vậy$y=6,25$

+$y$x$3,9=17,55$

$y=17,55:3,9$

$y=4,5$

Vậy $y=4,5$

$3)$

$12434cm=124,34m$

$22m35cm=22,35m$