The given equations are
y + 2x = 19
i.e., 2x + y = 19
2x 3y = 3
Comparing the given equations with a1x + b1y = c1 and a2x + b2y = c2,
we get
a1 = 2, b1 = 1, c1 = 19
a2 = 2, b2 = 3, c2 = 3
D = $|("a"_1, "b"_1),("a"_2, "b"_2)|$
= $|(2, 1),(2, -3)|$
= 2 ( 3) 1 2
= 6 2
= 8
