Efectuează calculele,apoi verifica prin adunare.

61+23=84
23+61=84
99-52=47
47+52=99
52+47=99
75-23=52
52+23=75
23+52=75
91-80=11
11+80=91
80+11=91
84-23=61
61+23=84
23+61=84
99-52=47
52+47=99
47+52=99
75-23=52
52+23=75
23+52=75
91-80=11
11+80=91
80+11=91