Consider the amount of gas in your car during a road trip. You start out with 40 gallons and drive for 4 hours, leaving you with 24 gallons in the tank. You stop for lunch for 2 hours and then drive for 2 more hours, leaving you with 16 gallons.

t= time

C (t)=_____ if 0 less than or equal to t less than or equal to 4.

C (t)=____ if 4 <t less than or equal to 6.

C (t)=___ if 6 <t less than or equal to 8.

why the inconsistency?

Either say

4 less than t less than or equal to 6
or, my favorite,
4 < t <= 6
For that piece, we have
C(t) = 4 for 4 < t <= 6

see what you can do with the others.