SOLUTION: Studio A Studio B classes|cost Classes|cost 3 70 4 80 7 130

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Question 1204546: Studio A Studio B
classes|cost Classes|cost
3 70 4 80
7 130 6 120
8 145 9 180
12 205 11 220
The tables above show the cost of yoga classes at two different studios. Studio A charges a mat fee of $25, but Studio B has no initial fee. Write a system of equations that will determine when the two studios cost the same.

Found 2 solutions by math_tutor2020, MathLover1:
Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

Given info
 Studio A                            Studio B
classes|cost                       Classes|cost
3        70                          4     80
7        130                         6     120
8        145                         9     180
12       205                         11    220


x = number of classes
y = total cost

Two ordered pairs with studio A are: (3,70) and (7,130)

Let's use the slope formula on those points.




m+=+%28y%5B2%5D+-+y%5B1%5D%29%2F%28x%5B2%5D+-+x%5B1%5D%29

m+=+%28130+-+70%29%2F%287+-+3%29

m+=+%2860%29%2F%284%29

m+=+15
The slope 15 means the cost goes up $15 each time you take a new class.
In other words, studio A charges $15 per class. This is on top of the $25 mat fee.
We arrive at the equation y+=+15x%2B25
As a check, plug in x = 3 and you should get the result y = 70. I'll let the student do this confirmation and check the other values as well.

Follow similar steps for studio B and you should get y+=+20x


The system of equations is therefore
system%28y+=+15x%2B25%2C+y+=+20x%29
x = number of classes
y = total cost

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
Studio A
classes|cost
3|+70
7|+130+
8|+145
12|+205
equation:
y=mx%2Bb
slope m=%28130-70%29%2F%287-3%29=15
Studio A charges a mat fee of $25, so b=25
y=15x%2B25....eq.1

Studio B
Classes|cost
4|+80
6|+120
9|+180
+11|+220
y=mx%2Bb
slope m=%28120-80%29%2F%286-4%29=20
Studio B has no initial fee, so b=0
y=20x....eq.2

a system of equations
y=15x%2B25....eq.1
y=20x....eq.2
---------------------------left sides are equal, so
15x%2B25=20x
25=20x-15x
5x=25
x=5
the two studios cost the same if the number of classes is 5
check
Studio A
y=15%2A5%2B25=75%2B25=100....eq.1
Classes|cost
5|100

Studio B
y=20%2A5=100....eq.2
Classes|cost
5| 100