Answer:

Step-by-step explanation:
Given



Required
Determine the coordinates of the centroid
Represent the coordinates with C.
C is calculated as follows:

Substitute values of x and y in the given equation



<em>The above is the coordinate of the centroid</em>
Try to understand this. Hope this help. Answer for 2 only.
Answer:
21 + 14x - 56 - 42x + 168
= 133 - 28x
Step-by-step explanation: