С×6=360 7×a=490 360:a=60 490: a=70 X:6=60 C:7=70
С*6=360; c=360:6; c=60. 7*a=490; a=490:7; a=70. 360:a=60; a=360:60; a=6 490:a=70; a=490:70; a=7 x:6=60; x=60*6; x=360. c:7=70; c=70*7; c=490.