315 + ( 125 -x ) = 435
( 125 - x ) = 435 - 315
125 - x = 120
x = 125 - 120
x = 5
a)
315 + ( 125 - x ) = 435
=> 125 - x = 435 - 315 = 120
=> x = 125 - 125 = 5
b)
3.x - 15 = 81
=> 3.x = 81 + 15 = 96
=> x = 96 : 3 = 32
c)
575 - ( x - 70 ) = 445
575 - x + 70 = 445
=> 575 + 70 - x = 445
=> 645 - x = 445
x = 645 - 445 = 200
Ủng hộ mik nhá ^_^"
315+(125-X)=435
125-X =435-315
125-X =120
X = 125-120
X =5
3X-15=81
3X = 81+15
3X = 96
X = 96 :3
X = 32
575-(X-70)=435
X-70 =575-435
X-70 =140
X =140+70
X = 210
CHỌN BÀI MÌNH NHÁ
a﴿
315 + ﴾ 125 ‐ x ﴿ = 435
=> 125 ‐ x = 435 ‐ 315 = 120
=> x = 125 ‐ 125 = 5
b﴿
3.x ‐ 15 = 81
=> 3.x = 81 + 15 = 96
=> x = 96 : 3 = 32
c﴿
575 ‐ ﴾ x ‐ 70 ﴿ = 445
575 ‐ x + 70 = 445
=> 575 + 70 ‐ x = 445
=> 645 ‐ x = 445
x = 645 ‐ 445 = 200
TK mik nhá ^_^"