Straight-line graphs 2

Find the gradient using the first two co-ordinates, and then substitute back into y=mx+c with known values, then solve for x.

I find the equation for the first the two points, which is y= 2x + c, then what do I need to do?

Nice, that’s what you should’ve got. Now, you can find a value for c by substituting one set of co-ordinates as your x and y values, and then solving for c. So, say you’re using the first set of co-ordinates, let x=-3, y=-2 and m=2 like you’ve just figured out. Now you can easily get a value for c.

Now that you have a complete equation, you can substitute y for 16 and x for k and then solve for k.

And I finally got 6! Thanks a bunch for guiding me through the question.
Is it ok if you help me through another question on this topic?
'Here are two straight lines. AB is parallel to PQ(Passes through 5 on y). The equation of the line AB is y = 4x + 1. Find the equation of the straight line PQ.'
In the question hint, it says:
'Find the gradient of AB.
Find the value of the y-intercept for PQ.
Use y = mx + c to find the equation of PQ.'

And I finally got 6! Thanks a bunch for guiding me through the question.
Is it ok if you help me through another question on this topic?
'Here are two straight lines. AB is parallel to PQ(Passes through 5 on y). The equation of the line AB is y = 4x + 1. Find the equation of the straight line PQ.'
In the question hint, it says:
'Find the gradient of AB.
Find the value of the y-intercept for PQ.
Use y = mx + c to find the equation of PQ.'

For two lines to be parallel, they must have the same gradient, else they will cross each other somewhere. Remember that, it's key for your understanding of this kind of topic in maths, especially if you plan to take maths beyond GCSE.

You've pretty much got the question with just that information.