The pythagorean theorem is more apt for the problem
This is the Identity property of addition. anything+0=that same number
Since adding 0 to a number still makes it the same number, its "identity" is still the same, thus the name.
Answer: 
Step-by-step explanation:
Given
Luis used 590 gm of flour each day
If he continues to use it for 3 weeks
A week has 7 days; so 3 weeks have 21 days
The flour used in 21 days

Thus,
of flour is used in 3 weeks
Answer:
4.6
Step-by-step explanation:
The net change is found by subtracting the starting number from the change. 2.2 minus -2.4 is 4.6. If this is wrong I apologise.