a) 13/36 x ( 7/26 + 1/13)=
13/36 x ( 7/26 + 2/26)=
13/36 x 9/26= 1/4 x 1/2 =1/8
simplific 9 si 36 prin 9 , simplific 13 si 26 prin 13
b) 6/31 x ( 2intreg 1/5 - 1intreg 1/6)=
2intreg 1/5= (5x2+1)/5=11/5
1intreg 1/6= (6x1+1)/6=7/6
6/31 x ( 11/5 -7/6)=
6/31 x ( (6x11)/30 - (7x5)/30)=
6/31 x (66-35)/30=
6/31 x 31/30=
simplific 31 si 31, simplific 6 si 30 prin 6
1/1 x 1/5= 1/5