Selesaikan (30 poin) Kunci Jawaban: 5 Lengkapi dengan cara.

Jawaban : -85/21 (tidak ada di pilihan)
Pembahasan ada di lampiran

9/x - 14/y = 0 (× 1)
6/x + 2/y = 1 (× 7)

...9/x - 14/y = 0
42/x + 14/y = 7
---------------------- +
51/x = 7
x = 51/7

9/x - 14/y = 0
9(51/7) - 14/y = 0
63/51 - 14/y = 0
14/y = 63/51
y = 14/(63/51)
y = 714/63
y = 34/3

x - y
= 51/7 - 34/3
= 153/21 - 238/21
= -85/21
= -4 1/21