To graph y = 4, we make a horizontal line at 4 on the y axis. See image 1
Since it is a horizontal line on the y axis, no matter the input you have for x, the y value is going to be 4. So the points <span> (4, ) (5, ) = </span><span> (4, 4) (5,4 )
For your point ( , 2.59), this is saying y = 2.59 The missing value would be 0. our points are below assuming the information given is complete:
</span>(4, ) (5, ) ( ,2.59) = (4, 4) (5,4 ) (0,2.59)