When calculating angle of incidence, I do latitude-tilt.

I was solving two similar problems from the class. These two problems are both asking about angle of incidence of the sunlight at different latitude. First one was asking New Zealand(latitude 43degree south of the equator)’s angle of incidence, which was -43-23.5= -66.5 degree, and I had no problem with that. However, the second one was asking Toronto(latitude 44degree north of the equator)’s angle of incidence, and the answer was 44-(-23.5)=67.5 degree. I understand that latitude turns to positive number when it is at the north of the equator, and negative at the south of the equator, but why did earth’s tilt angle turn to negative 23.5 on the second problem?

That’s the only question I have. Why is it negative 23.5 on the second problem?