Answer: May not be the exact answer you're looking for, but the explanation below should make sense.
Explanation:
To shift the graph of y=2x+5 up, there is no need for a seperate equation. When you notice is that 5 is the y-intercept. Since the slope of the equation is still the same, all you do is increase the y-intercept to shift it up and decrease to shift it down. This may be a little hard, but if you graph it, and mess around with the y-intercept, you will see that the graph goes up as the y-intercept increases. As you decrease the y-intercept, the graph will travel down.
I hope this answers your question. Let me know if you have any questions.