Find the distance between the given parallel planes.

Question

5x−4y+z=10, 10x−8y+2z=3

Answer 1

here is an example of how to do this:
http://www.math.ucla.edu/~ronmiech/Calculus_Problems/32A/chap11/section5/718d65/718_65.html

Answer 2

point in first plane
0,0 something
(0 , 0 , 10)

d = | 10*0 -8*0 +2*10 -3 | /sqrt(10^2+8^2+4^2)

= 17/13.4