Problema Solution
An University bookstore recently sold a wirebound graph-paper notebook for $1.64, and a college-ruled notebook for $1.17. At the start of spring semester, a combination of 50 of these notebooks were sold for a total of $66.02. how many of each type were sold?
Answer provided by our tutors
Assume that the number of wire-bound notebooks is represented by x and the college-ruled notebook is y.
The problem then says that the quantity of x & y = 50
The problem also says that the amount sold equaled 66.02, so that means that 1.64x + 1.17y = 66.02
A system of equations like this can be solved by substitution, where you find the value of one variable in one equation, then plug that into the second. For the first, solve for x:
x + y = 50
x = 50 - y
Take that (50 - y) and plug it in for x in the second equation (since they're both the same value):
1.64(50 - y) + 1.17y = 66.02
Now you only have one variable to solve for right now:
82 - 1.64y + 1.17y = 66.02
82 - 0.47y = 66.02
-0.47y = -15.98
y = 34
The store sold 34 college-ruled notebooks, so putting that back into the first equation will give you an x-value of 16 wirebound notebooks.