Tolong dijawab ya pliss besok dikumpulkan

4. (0,8)(8,0)
ax+by = a.b
=8x+8y = 64 (dibagi 8)
= x + y = 8 ..........1

(0,6)(9,0)
ax+by= a.b
=6x+9y = 54 [dibagi 3)
= 2x + 3y = 18...........2
jadi simtem pertdaksamaannya
x+y < 8, 2x + 3y > 18, x > 0, y > 0

6. x - y > -2 (0,2)(-2,0)
x - 3y < 3 (0,-1)(3,0)
4x + 5y < 20 (0,4)(5,0)
x > 0, y > 0