Answer:
x = -1 & y = -9
Step-by-step explanation:
The given equations are
7x - 3y = 20 ⇒(1)
y = 5x - 4 ⇒ (2)
multiplying (2) by 3
3y = 15x - 12 ⇒ (3)
Add (1) and (3)
∴ 7x - 3y + 3y =20 + 15x - 12
∴ 7x = 15x + 8
∴ 7x - 15x = 8
∴ -8x = 8
∴ x = -1
substitute by x at (2)
∴ y = 5 * (-1) - 4 = -5 - 4 = -9
So, x = -1 and y = -9
