Sean tried to drink a slushy as fast as he could. he drank 5 milliliters of slushy each second and finished all the slushy after 50 seconds. how do i graph this ?

-- Take a piece of paper.

-- Take a pencil or a pen.

-- On the paper, draw an x-axis and a y-axis.

-- Number the x-axis from zero to at least 50 seconds.
(You may want to mark it by 5s or 10s, so it won't take all day.)

-- Number the y-axis from zero to at least 250 milliliters.
(You may want to mark it by 10s or 20s or 25s so it doesn't take all day.)

-- Mark a dot at the point (0, 0).
This point shows that when the clock started, Sean
had not swallowed ANY of the slushy so far.

-- You only need one more dot on the graph.  Once you have it,
you can draw a straight line between the two dots.
The only question is:  Where to put the second dot ?

Well, you know that Sean is drinking 5 milliliters every second.
So he'll drink, let's say ...

10 ml after 2 seconds
20 ml after 4 seconds
25 ml after 5 seconds
50 ml after 10 seconds
75 ml after 15 seconds
100 ml after 20 seconds
150 ml after 30 seconds
200 ml after 40 seconds
.
.
.

ANY one of these points can be the second dot on your graph. 

-- When you have TWO dots on the graph, take a RULER.

-- Put the ruler down on the graph in a position where both dots
are right on the edge of the ruler.

-- Take the pencil or pen.  Following the edge of the ruler, draw
the straight line. 
Start at (0,0,), draw the line to the second dot.
Then you can keep the line going, all the way to (50, 250). 
That's where Sean finished the total slushy, and grabbed his nose
to try and stop the brain freeze, while he ran to the bathroom to
throw up.