12tttttttttttttttttttttttt
Answer:

Step-by-step explanation:
The equation that will model this situation will be of the form
where
is the time in hours john has traveled since the gas station, and
is the distance.
Now we know that John has already traveled 20 miles when he is at the gas station, this means at
,
; or


Thus we have
.
Now we need to figure out 
When John reaches home 2 hours later he notes that he has traveled 30 miles, which means he has traveled 30 - 20 = 10 miles; thus we have


Now we have the full equation:

Answer:
all real numbers
Step-by-step explanation:
The graphs of positive and negative x^2 parabolas will always have a domain of all real numbers. Even though you only have a portion of the graph and see a "restriction" on your domain values, it is incorrect to assume that the domain is limited to what you can see. As the branches of the parabola keep going up and up and up, the values of x keep getting bigger and bigger and bigger. Again, this is true for all + or - parabolas. ....... Can consider brainlist*:)