Tolong jawab ya, pake cara juga, makasih

Program linier

garis melalui (0,4) dan (5/2, 0)
4(x) + 5/2(y) = 4(5/2)
4x + 5/2 y = 10
8x + 5y= 20

titk potong 8x + 5y = 20 dengan x = 2/3
8(2/3)+ 5y = 20
5y = 20 - 16/3
5y = 44/3
y = 44/15

z= 1/3 (2x - y)  untuk titik pojok daerah HP :
(2/3 , 44/15) --> z = 1/3 ( 2(2/3) - 44/15) = 1/3 (4/3 - 44/15) = 1/3 (- 8/5) = - 8/15
(5/2, 0)  --> z =1/3 ( 2(5/2) - 0) = 1/3 ( 5) = 5/3 = 15/9