A sine function has a max value of 7, min value of -1. Phase shift is 3pi/4 to the left. Period is pi/2

Write an equation for the function and then graph the function..

Ok, I did this question, and my equation was something like this:

y=4sin(4(x+3pi/4))

However, in the back of the book. The answer is y=4sin(4(x+3pi/4))+3

The k value in the equation? I am not sure how to get this k value.

How would I figure this out? Am I wrong or is it wrong in the back?

thank you