C. a person who is in a monogamous relationship and has protected sex.
D lack of time cause time management can make people not do things they wish
The best answer for the blood vessels' valves would be these are veins that would then help in preventing the back flow of blood because the walls have small muscle to pump the blood back to the heart.Hope this is the answer.
Answer:
a+4b
Explanation:
Since the length is 4a-2b, that means there is 2 of those, since the perimeter is 2l+2w, which basically means 2 values of the length plus 2 values of the width. In this case, the length is 4a-2b so that means we have to subtract twice its value from the perimeter, 10a+12b.
When you do that, you get 2a+8b, which must be divided into 2 because there is supposed to be 2 values of the width. That gets you your final answer, a+4b.
