1) 2 11/12: 7/8= 7,5
2) 14- 7,5= 6,5
3) 6,5: 4 7/8= 1 1/3
Биссектриса делит угол пополам, значит BAD= 1/2 BAC = 64/2=32 градуса
(6/7 - y) + 2/7 = 5/7
6/7 - y = 5/7 - 2/7
6/7 - y = 3/7
y = 6/7 - 3/7
y = 3/7
(6/7 - 3/7) + 2/7 = 5/7
5/7 = 5/7
{20 - (3а - 7)} /10 = 9/10
20 - (3а - 7) = 9/1 = 9
20 - (3а - 7) = 9
3а - 7 = 20 - 9
3а - 7 = 11
3а = 7 + 11
3а = 18
а = 18 : 3
а = 6