SOLUTION: Eight students in Ms. Reese's dass decided to purchase their textbook from two different sources. Some of the students purchased the textbook from the college bookstore for 16.50.

Question 1168462: Eight students in Ms. Reese's dass decided to purchase their textbook from two different sources. Some of the students purchased the textbook from the college bookstore for 16.50. The rest of the students purchased the textbook from an online discount store for S13.00 per book. If the total amount spent by the eight students is 118.00, how many students purchased the book online?
Found 2 solutions by mila nedic, MathTherapy:
Answer by mila nedic(19) (Show Source): You can put this solution on YOUR website!
Let's say the number of students who purchase online are "o" and the number of students who purchase from the bookstore are "b". Simply put o=online and b=bookstore.
We know that there are 8 students meaning o+b=8
We also know that the total amount spent by all 8 students was $118 so
16.5*b+13*o=118
Since there are two variables o and b, we want to simplify it so we only have one of them.
o+b=8 can be changed to isolate o by subtracting each side by b, changing the equation to o=8-b. Now we can input 8-b instead of o in the original 16.5*b+13*o=118 equation so we are only dealing with one variable for now.
Inputting o=8-b into 16.5*b+13*o=118 would change it to 16.5*b+13*(8-b)=118
Now we can simplify the brackets by multiplying 13 by 8-b.
The equation would then look like 16.5*b+((13*8)-(13*b))=118 which is the same as 16.5b+104-13b=118 (we can now isolate the b's by subtracting 104 from each side and putting the b's together)
16.5b+104-13b=118 can be simplified to 3.5b=14
Now we can divide both sides by 3.5 to isolate b.
b=14/3.5
b=4
If we know that 4 students purchased books from the bookstore then we can figure out how many purchased online if we use the first equation we established which was o+b=8.
We can input 4 instead of be since we found out that b=4. So o+4=8. To isolate "o" we have to subtract both sides by 4 which would give us o=4.
Therefore, 4 students purchased their book online.
Answer by MathTherapy(10556) (Show Source): You can put this solution on YOUR website!

Eight students in Ms. Reese's dass decided to purchase their textbook from two different sources. Some of the students purchased the textbook from the college bookstore for 16.50. The rest of the students purchased the textbook from an online discount store for S13.00 per book. If the total amount spent by the eight students is 118.00, how many students purchased the book online?

Let number of students that bought book online be S
Then number of students that bought book at bookstore = 8 - S
Amount spent by students who bought book online: 16.5S
Amount spent by students who bought book at bookstore: 13(8 - S), or 104 - 13S
We then get: 16.5S + 104 - 13S = 118
16.5S - 13S = 118 - 104
3.5S = 14
Number of students that bought book online, or
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