If 7x – 5y = 20 and 12x + 5y = 75, what is the value of xy ?

$herefore x=frac{95}{19}=5$

Now,

7x – 5y = 20

⇒ 7 × 5 – 5y = 20

⇒ 5y = 35 – 20 = 15

$herefore y=frac{15}{5}=3$

$x y=5 imes 3=15$