(1,2)(4,-1)
slope = (y2 - y1) / (x2 - x1)
slope = (-1 - 2) / (4 - 1) = -3/3 = -1
the slope is -1......I am not sure of the mistake.....unless she just added (-1 - 2) and got 3 instead of -3.......or when dividing -3/3....she maybe forgot about the negative sign
The product of a number y and 12 or 12 times a number y. These are both equivalent expressions to 12y
Answer:

The world population at the beginning of 2019 will be of 7.45 billion people.
Step-by-step explanation:
The world population can be modeled by the following equation.

In which Q(t) is the population in t years after 1980, in billions, Q(0) is the initial population and r is the growth rate.
The world population at the beginning of 1980 was 4.5 billion. Assuming that the population continued to grow at the rate of approximately 1.3%/year.
This means that 
So


What will the world population be at the beginning of 2019 ?
2019 - 1980 = 39. So this is Q(39).


The world population at the beginning of 2019 will be of 7.45 billion people.
The answers should be: (-2,5), (-2,-2), (-6,-1), (2,1)
Hope this helped :)
Can you explain it more clear because my english is not very good, I want to easy to help you