Yes because when you subtract a number, you can also say that you added a negative. So if it dropped 23 degrees, then you also added -23 degrees
To calculate minimum value, do -b/2a to get the x-value, and plug it in to get the y-value:
-6/8 = -3/4

So the minimum value of g(x) is -81/4
This shows that g(x) has a lesser minimum value than f(x)
T=26
you just add 7 to the other side with 19 which gives you the answer