1) 2 1/2* 6+3 1/3= 5/2*6+10/3=30/2+10/3=90/6+20/6=110/90=11/9=2 2/9
2) 2 1/2*2 + 3 1/3*3=
5/2*2+20/3*3=5+20=25
3) 17:(4 1/3 - 3 1/3)=
17÷(13/3-10/3)=17÷3/3=17÷1=17
4) (15 - 4 1/8) * ( 3 14/15 - 2 3/5)=
10 7/8*(59/15-13/5)=10 7/8*(59/15-39/15)=10 7/8*20/15=87/8*4/3=29/2=14,5