Answer:

Step-by-step explanation:
I assume that the three points given are the vertices of the triangle. So the three points are:
A (-4,1)
B (-7,5)
C (0,1)
The area of a triangle is given by:

where b is the base and h is the height.
Here we can take as follows:
- We can take the base to be the side AC, so that its length is equal to the distance between the two points:

- The height of the triangle is therefore the perpendicular distance between AC and point B. This is equivalent the difference in the x-coordinate between any point on AC and B, so:

Therefore, the area of the triangle is:

Step-by-step explanation:

here ( + ) × ( - ) = ( - )




Answer:
25
Step-by-step explanation:
We need to set up a system of equations, then solve for the number of board markers.
Let r represent red pens, let b represent board markers.
She has 41 items, so our first equation is r+b=41.
The total cost is $46.30, so our second equation is .55r+1.5b=46.3.
r+b=41
.55r+1.5b=46.3
Let's use substitution.
r+b=41
r=41-b
.55r+1.5b=46.3
.55(41-b)+1.5b=46.3
22.55-.55b+1.5b=46.3
22.55+.95b=46.3
.95b=23.75
b=25
He bought 25 board markers.
Step-by-step explanation:
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