5 часов и 11 минут- решение
5y-25=30
Неизвестное влево, а известное вправо.
5y=30+25
5y=55
y=55:5
y=11
56:y+107=144
56:y=144-107
56:y=37
y=56:37
y=1,51
(6,5-1,3х)*4/13=(0,8-3):6/7
13/2*4/13-13/10х*4/13=-11/5*7/6
2-2/5х=-77/30
-2/5х=-77/30-2
-2/5х=-4 17/30
Х=-137/30*(-5/2)
Х=137/12
Х=11 5/12
1) (1/12+1/6) : (3/8-1/4) = (1/12+2/12) : (3/8-2/8) = 3/12 : 1/8 =1/4 * 8/1 = 2
2) (1 - 4/9) : (1/3 -1/4) = 5/9 : (4/12 - 3/12) = 5/9 * 12/1 = 20/3 = 6 2/3
3) (1/3 -5/16) : (1/6-1/8) = (16/48 - 15/48) : (4/24 - 3/24) = 1/48 : 1/48 = 1
4) (5/7 - 2/3) : (4/9 - 5/12) = (15/21 - 14/21) : (16/36 - 15/36) = 1/21 : 1/36 =
= 1/21 * 36/1 = 36/21 = 12/7 = 1 5/7