(7+□):8=2 (19+□):9=3 (□□-4):7=8 (42-□□)*5=30 54:(□□-7)=9 (□□-30)*6=54
(7+9):8=2 (19+7):9=3 (60-4):7=8 (42-36)×5=30 54:(13-7)=9 (39-30)×6=54