а) (1/2 + 1/5) : 2 - 3/10 =
б) (3/4 - 5/12) * 8 + 1/18 =
(1/2 + 1/5) : 2 - 3/10 = ((5+2)/(10*2))-((3*2)/(10*2))=1/20
(3/4 - 5/12) * 8 + 1/18 =49/18
Б) (3/4 - 5/12) * 8 + 1/18 =49/18