In case of parallel lines
![(a1)/(a2) = (b1)/(b2) \: not \: equal \: to \: (c1)/(c2)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/x8mx08n8ktevguhp8m2fjc5e08sspkmf2l.png)
Where a1, b1 and c1 are the constants of the first equation and a2, b2 and c2 are the constants of the second equation
From first equation (5x+10y+4 = 0)
a1 = 5
b1 = 10
c1 = 4
So now what we want to do is to divide 5 by a number and 10 by another number to get the same result at the end
I'll divide 5 by 1 and 10 by 2 to get the same number 5
5/1 = 10/2
Then I'll divide 4 by any number to get a result other than 5
Let's say 4 (or any other number it can be positive as well as negative)
So
a2 = 1
b2 = 2
c2 = 4
Then now the last step is to write the equation using these constants
x + 2y +4 =0
x+2y= - 4
Therefore this equation is parallel to 5x+10y = - 4