Answer is option 4. working out attached
hope it helps :)
Answer:


Step-by-step explanation:
Given
See attachment for complete question
Required
Express the answer in 
From the question, we have:

breath/person in a year
The number of breath is calculated by:

So, we have:

Reorder



Using scientific notation
;
The value (a) must be in the following interval 
So, we have:


By comparing the above with: 


Answer:
the little box would indicate that it is a 90 degree angle.
Answer:
Step-by-step explanation:
6.50$
Answer:
21
Step-by-step explanation:
14+7=21.
You do this to allow you to get that outcome, because you know 7*7=49.
Therefore 21-14=7
7*-7=49