x = 4, y = 2

Given: x - 2y = 0 … (1)

3x + 4y = 20 …(2)

By elimination method,

Step 1: Multiply equation (1) by 3 and equation (2) by 1 to make the coefficients of x equal.

Then, we get the equations as:

3x – 6y = 0 … (3)

3x + 4y = 20 … (4)

Step 2: Subtract equation (4) from equation (3),

(3x – 3x) + (4y + 6y) = 20 – 0

⇒ 10y = 20

y = 2

Step 3: Substitute y value in (1),

x – 2(2) = 0

⇒ x = 4

The solution is x = 4, y = 2.