Question 3 is: D. All integers are rational numbers.
Question 4 is: C. the counting number is 4. Hope this helped :)
Answer: 185 sorry if wrong
Answer:

Step-by-step explanation:
Given:
A car starts with a dull tank of gas
1/7 of the gas has been used around the city.
With the rest of the gas in the car, the car can travel to and from Ottawa three times.
Question asked:
What fractions of a tank of gas does each complete trip to Ottawa use?
Solution:
Fuel used around the city = 
Remaining fuel after driving around the city = 1 -
= 
According to question:
As from the rest of the gas in the car that is
, the car can complete 3 trip to Ottawa which means,
By unitary method:
The car can complete 3 trip by using =
tank of gas.
The car can complete 1 trip by using = 
=
= 
=
tank of gas
Thus,
tank of gas used for each complete trip to Ottawa.
Answer:
Step-by-step explanation:
cos ^-1(0)=(2n+1) π/2
where n is an integer.
if 0 ≤α ≤2 π
n=0,1
cos ^-1(0)=π/2,3π/2