tolong jawab pakai cara ya!!!! nomor 18

misalkan 1/x = a dan 1/y = b
maka persamaannya menjadi:
3a+4b=7 x1
5a-2b=3 x2

3a+4b =7
10a-4b= 6
------------- +
13a = 13
a = 1

subtitusi
3a+4b=7
3.1+4b = 7
3 +4b = 7
4b = 7-3
4b= 4
b = 1

maka
x=1/a = 1/1 = 1
y = 1/b = 1/1 = 1

hasil kali x . y = 1 .1 = 1