112 - (x+4)=1339:13
112 - (x+4)=103
x+4= 112-103
x+4=9
x=9-4
x=5
_________
468+85xX=2508
85 x X = 2508 - 468
85 x X = 2040
X= 2040 : 85
X=24
____
Xx2,5=2,5x4
X x 2,5 = 10
X= 10:2,5
X=4
________
x-270:45=120
X - 6 = 120
X= 120+6
X=126
575-(6xX)+70=445
(6 x X) + 70 = 575 - 445
(6 x X) + 70= 130
6 x X = 130 - 70
6 x X = 60
X= 60:6
X=10
______
x-105:21=15
X - 5 = 15
X= 15+5
X=20
______
3200:(405-x)=8
405 - x = 3200 : 8
405 - x = 400
x= 405 - 400
x= 5
_______
43575-75xX=42450
75 x X = 43575 - 42450
75 x X = 1125
X= 1125:75
X= 15
______
8,75xX+1,25xX=20
(8,75 + 1,25) x X = 20
10 x X = 20
X=20:10
X=2