(5/12-1/19)*12-7/9應該怎樣簡算

(5/12-1/19)*12-7/9應該怎樣簡算

(5/12-1/19)*12 -7/19後邊是7/19吧
=5/12*12-1/19*12 -7/19這一步是用乘法分配律
=5- 12/19 -7/19
=5-(12/19+7/19)連减可以等於减去它們的和
=5-1
=4