Explicație pas cu pas:
a)4830+x=7031
x=7031-4830
x=2201
b) 13043+x=13093
x=13093-13043
x=50
c) 850-x=140
x=850-140
x=710
d) 1243-x=947
x=1243-947
x=296
e) 12342+x=12943
x=12943-12342
x=601
f) 15013-x=471
x=15013-471
x=14542
g) 438+x-148=572
438+x=572-148
438+x=424
x=14
h) x-170+372=602
x-170=602-372
x-170=230
x=230+170
x=400
i) 831+x+169=1000
831+x=1000-169
831+x=831
x=831-831
x=0
Succes!