Найдите значение выражения: а) (3+1 13/15) * (1-1/3) б) 15: (2/5+1/15+4/25)

Найдите значение выражения

а) (3+1 13/15) * (1-1/3) = 3 11/45

1)) 3+1 13/15 = 4 13/15

2)) 1-1/3 = 3/3 - 1/3 = 2/3

3)) 4 13/15• 2/3 = (4•15+13) / 15 • 2/3 = 73/15• 2/3 = 146/45 = 3 11/45

б) 15: (2/5+1/15+4/25) = 23 44/47

1)) 2/5 + 1/15 + 4/25 = (2•15) / (5•15) + (1•5) / (15•5) + (4•3) / (25•3) = 30/75 + 5/75 + 12/75 = 47/75

2)) 15: 47/75 = 15/1• 75/47 = 1125/47 = 23 44/47