Tolong bagi ilmu Pakai caranya juga

Bab Persamaan Linear
Matematika SMP Kelas VIII

13] (3x + 1)/2 + (6y + 3)/5 = -1
※※※dikali 10※※※
15x + 5 + 12y + 6 = -10
15x + 12y = -10-11
15x + 12y = -21

2x + 2 + (3y + 6)/2 = 3
4x + 4 + 3y + 6 = 6
4x + 3y = -4
16x + 12y = -16

16x + 12y = -16
15x + 12y = -21
--------------------- -
x = 5

4x + 3y = -4
3y = -4 - 4 . 5
y = -24 : 3
y = -8

◎◎ B ◎◎

14] 6j = 5a
6j - 5a = 0
12j - 10a = 0

4j + 3a = 114
12j + 9a = 342

j + 2a = ?

12j + 9a = 342
12j - 10a = 0
------------------------- -
19a = 342
a = 18

6j = 5a
j = 5 x 18 : 3
j = 30

j + 2a
= 30 + 2 x 18
= 66
= Rp 66.000,00