а) 50-46=4
53-50=7-4
49-46=7-4
53+46=49+50
б)57-37=65-45
28-8=57-37
28-8=65-45
28+8=36
а)49+4=53
53-49=4
46+7=53
50-4=46
50-46=4
б)28+8=36
57-37+8=28
57+8=65
65-28=37
