SOLUTION: 1.) Sales last month were 4000.00, this month they were 5000.00. Write an equation that shows this using y for sales and x for the month. (this month x=0, last month x=-1, next mon

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Question 53924: 1.) Sales last month were 4000.00, this month they were 5000.00. Write an equation that shows this using y for sales and x for the month. (this month x=0, last month x=-1, next month x=1 etc... 2.) What will the sales be 4 months from now?
Can someone show me how to work this? Thanks.

Answer by funmath(2873) About Me  (Show Source):
You can put this solution on YOUR website!
Let the coordinates for last month(x1,y1)=(-1,4000)
Let the coordinates for this month (x2,y2)=(0,5000)
Notice that (0,5000) is the y intercept (0,b).
All we need to find is the slope (m).
The slope formula is:
m=%28y2-y1%29%2F%28x2-x1%29
m=%285000-4000%29%2F%280-%28-1%29%29
m=1000%2F1
m=1000
The slope intercept form of a line is:
y=mx+b, where m=slope, and (0,b)= y intersept.
Therefore the equation is:
y=1000x+5000
-----------------------
In four months x=4, substitute that into the equation for x and solve for y. Remember y is how much sales they think thy're going to make if this trend continues.
y=1000(4)+5000
y=4000+5000
y=9000
y=9000.00
Happy Calculating!!!!