I believe it is B. You should be correct
Answer:
The area of the room and its uncertainty in square meters is:
15.642±0.040 
Step-by-step explanation:
We know the area of a rectangular room is the multiplication of the length and width:

Now we need to know the uncertainty, the uncertainty of a multiplication is:
(1)
: Area uncertainty
: Length uncertainty
: Width uncertainty
A: Area of the room
L: Length
W: Width
Clearing the uncertainty of the area:
(2)


The area of the room and its uncertainty in square meters is:
15.642±0.040 
Doing 2 strategies at one time or in a certain order
Answer:
18cm
Step-by-step explanation:
We have the length of the rectangle but we need to find the width which we'll call w. Area is a, l is length.
a = l * w
20 = 5 * w
divide both sides by 5 to cancel the multiplication by 5 on the right side
4 = w
The rectangle is going to have two sides that are the length of l, and two sides that are the the length of w. We're looking for the perimiter p.
p = 2l + 2w
p = (2 * 5) + (2 * 4)
p = 18
The answer should be A because when you multiply two negatives it comes out positive