As a group they were paid $1000 after putting in 4+6+5+5 = 20 worker-hours.
$1000/(20 worker-hours) = $50/(worker-hour)
Alemu received 4*$50 = $200
Tulu received 6*$50 = $300
Kassa and Tegitu each received 5*$50 = $250
The picture below shows the formula for calculating slope
In this example:
y2 = 4
y1 = -4
x2 = 5
x1 = 3
(These are the numbers you substitute into the formula)
Calculations:
4 - (-4) = 8
5 - 3 = 2
8/2 = 4
As you can see, after the values are substituted into the equation & simplified, the slope is equal to 4
For this case we have the following equation:

Deriving we have:

We match zero:

We clear the value of x:

Then, we substitute the value of x in the equation of the parabola:

Thus, the vertex of the parabola is the ordered pair:
Answer:
The vertice is:
3-y/2=1
-3 -3
-y/2=-2
x2 x2
-y=-4
/-1 /-1
Y=4