Question 3 is: D. All integers are rational numbers.
Question 4 is: C. the counting number is 4. Hope this helped :)
Answer:
0.5hrs
Step-by-step explanation:
Let the speed downhill be
,
Speed uphill is
. We are told than speed uphill is
the speed on flat ground. Therefore the speed on level ground will be
.
From this info, we can obtain the actual speed,
on level ground as:

speed, distance and time have the relation
so to obtain time to cover 45miles:

Hence it takes 0.5hrs to cover 45miles on flat ground.
The rate of change is -2 :)
You set the corresponding sides equal to each other and solve for x as you would in a normal equation