Answer:
6
Step-by-step explanation:
1. re-write the given system:
cx+3y=c-3; => y= -cx/3 +(c-3)/3
12x+cy=c; => y= -12x/c+c/12
2. according the condition the rule for the parallel graphs is:
-c/3= -12/c
3. to calculate the unknown 'c':
c²=36; ⇔c=±6
123/0.75 =164
the answer is 164
For the function

We can use the formula for the axis of symetry, which is

With the values substituted, we get...

Therefore the axis of symmetry is
18/6 = 3
So the temperature dropped 3 degrees each day.
Hope this Helps!!