Step-by-step explanation:
You would solve it by turning it into a equation and solving it. You would place the dots on the graph and put them in the points where they are supposed to go.
Are you sure you wrote it right because it should be -42.99
Show me a picture of the equation
Answer:

Step-by-step explanation:
Given : Vertices of Triangle
,
and 
To find : Centroid of a triangle
The centroid of a triangle is the point of intersection of the three medians of the triangle.
The formula to calculate the centroid of a triangle is:

Where,
are the coordinates of the centroid
Substituting the values in the formula gives us:



Therefore, 
Answer:
Our two numbers are 50 and 20
Step-by-step explanation:
Sum means add together
Difference means subtract each other
x + y = 70
x - y = 30
subtract from each other
2x = 100
divide both sides by 2
x = 50
our first number is 50
50 + y = 70
subtract both sides by 50
y = 20
Our two numbers are 50 and 20