tolong ya, pakai cara :)

*1/2a-1/4b =2
(kali 4)
2a - 1b = 8

* 1/5a + 1/3b = 6
(kali 30)
6a + 10b = 180

spldv
2a-1b=8. /x3/ 6a-3b=24
6a+10b =180/x1/ 6a+10b =180 (kurangi)
-13b = -156
b= 12
6a-3b =24
6a - 3.12=24
6a -36 = 24
6a. = 60
a =10

nilai 2a-3b = 2.10 - 3.12
= 20-36
= -16
smoga bermanfaat....