Answer:
Step-by-step explanation:
Given
Equations are
and 
take 

Put the value of y in another equation

Put the value of x in y

Hence,
Answer:
13646514108
Step-by-step explanation:
Used calculator.
Answer:
400 cm squared
Step-by-step explanation:
Since a square has all equal sides, this would mean the the all the other sides are 20 as well. To get the area, you would just multiply 20 by 20 to get 400. :)
Lets round it to the nearest ten
A 97 ====> 100
B 118 ===> 120
C 179 ===> 180
D 5091 ==> 5090
No result yet, lets round to the nearest hindred.
A 97 ====> 100
B 118 ===> 100
C 179 ===> 180
D 5091 ==> 5100
As we can see only A give the same result when we round it to the nearest hundred and nearest ten.