The planes 2x-y+4z=5 and 5x-2.5y+10z=6 are

Planes are

$2x-y+4z=5$......(1)

$5x-2.5y+10z=6$......(2)

Multiply equation (2) by 2

$⇒10x-5y+20z=12$

Divide this equation by 5

$⇒2x-y+4z=\frac{12}{5}$

Now this equation parallel to (1)