Urgent help! Math oct/nov 2012 paper 21

[Mariam Mohamed SX132]

Assalamu Alikom,
I was solving pastpapers then I came across May/June 2012 paper 22 , and there were some questions that drove me crazy so can someone please explain:17 (b) and (c) page 10
http://olevel.sourceforge.net/papers/0580/0580_s12_qp_22.pdf
Thank you in advance and Good luck to all of you <3

 

[CaptainDanger]

Walikum Salaam!

b) Put the given coordinate (2, 6) in y = 4x + c
x = 2
y = 6
Solve.

c) As the lines are parallel, gradients will be same.
Make the given equations in y = mx + c form.
5x = 4y + 10
5x - 10 = 4y
(5x/4) - (10/4) = y
y = (5x/4) - (10/4)

2y = kx - 4
y = (kx/2) - (4/2)

Compare the gradients.
So k/2 = 5/4 ==> k = 5/2

 

[Mariam Mohamed SX132]

Thank youuu so muchhhhh!