с×6=210 с×3=240 210÷а=30 240÷а=30 х÷3=70 х÷3=60

c*6=210c=210:6c=3535*6=21035=35c•3=240c=240:3c=8080*3=240210:a=30a=210:30a=7210:7=30240:a=30a=240:30a=8240:8=308=8x:3=60x=60*3x=180180:3=60180=180