0.7*24.5+0.7*76.5-0.7簡算

0.7*24.5+0.7*76.5-0.7簡算

0.7*24.5+0.7*76.5-0.7=0.7X[(24.5+76.5)-1]
=0.7X(101-1)
=0.7X100
=70