a) 1-5/6 × ( 0,7 - 4/15) =
=1-5/6 × ( 7/10 - 4/15) =
=1-5/6 × ( 21 - 8)/30 =
=1-5/6 × 13/30=
=1-1/6 × 13/6 =
=1-13/36=
=(36-13)/36=23/36
b) 1- 0,9 ×( 7/12- 5/9 )=
=1- 9/10 ×( 21-20)/36=
=1- 9/10 ×1/36=
=1- 1/40=
=39/40
c) 1,02 + 49/50 -1,1(6) × 3/7=
= 102/100 + 49/50 -(116-11)/90 × 3/7=
= 51/50 + 49/50 -105/90 × 3/7=
= 100/50-7/6 × 3/7=
= 2-1/2=3/2