tolong di bantu ya kak no 1 dan 4

1.) Persamaannya
20x+12y=76000
17x+28h= 118000
Matriksnya
|20 12| |x| = |76000|
|17 28| |y| =|118000|
Maka,
x = |c1 b1|
|c2 b2|
----------------
|a1 b1|
|a2 b2|
Determinankan matriksnya
c1b2-c2b1
=----------------
a1b2-a2b1
76000(28)-118000(12)
=--------------------------------
20(28)-17(12)
2128000-1416000
=---------------------------
560-204
712000/356 = 2000
Maka x=2000, dan y=300

5.)