A + B = 8
+ +
C - D = 6
= =
13 6
ответ мне​

a + b = 8

a + c = 13

b + d = 8

c - d = 6

пусть b = x

тогда a = 8 - x

c = 13 - (8 - x)

d = 8 - x

c - d = (13 - (8 - x)) - (8 - x) = 6

13 - 8 + x - 8 + x = 6

2x - 3 = 6

2x = 9

x = 4.5

b = 4.5

a = 8 - x = 3.5

d = 8 - x = 3.5

c = 13 - (8 - x) = 13 - 3.5 = 9,5