(1) (2.4*4-3) / 1.5 =4.4
(2) 0.6*2.4 / (3.24-1.8) =1.25
(3) (3.5+1.5) / (3.5-1.5) =3
(4) (40-8.1*3) /0.4 =39.25
/是除号