(9+1)•40=400
9+1=10
10•40=400
(2+5)•30=210
2+5=7
7•30=210
(20+40)•6=360
20+40=60
60•6=360
(50+40)•8=720
50+40=90
90•8=720
(6+4)•7=70
6+4=10
10•7=70
(20+30)•8=400
20+30=50
50•8=400
(9+1)•40=400
9+1=10
10•40=400
(2+5)•30=210
2+5=7
7•30=210
(20+40)•6=360
20+40=60
60•6=360
(50+40)•8=720
50+40=90
90•8=720
(6+4)•7=70
6+4=10
10•7=70
(20+30)•8=400
20+30=50
50•8=400