8/23 *(3/4+1 1/6) 2 1/3 * 3/10: 2 4/5 (4-2 1/2 *3/5): 3 1/3 9,72 : 2,4

1) 8/23*(3/4 +7/6)=
=8/23*(9+14)/12=
=(8*23) /23*12 =8/12=2/3

2) 7/3 * 3/10 :14/5 =
=21/30 :14/5 =21*5 /30*14=
=3/6*2=3/12=1/4
при делении дробь переворачиваем и будет умножение, те 14/5=5/14

3) (4 -5/2*3/5) :10/3 =
=(4-15/10)*3/10= (40-15)/10 *
3/10=25/10 *3/10 =25*3 /100=75/100=0.75

4) 9.72: 2.4=
972/100:24/10=
=972/100 * 10/24 =
=972*10 /100*24=
=40.5 /10=4.05