Çözüldü Two-Variable Equations

A store sells shirts for $7.50 each and hats for $5.00 each. The store earns $1,822.50 in one day from selling a total of 307
shirts and hats. How many shirts were sold on that day?

A) 37
B) 89
C) 115
D) 202

Math Workout for the SAT

Classic Algebra Solution:
If the number of shirts and hats sold on that day are s and h respectively, then the equations;
s + h = 307
7.5·s + 5·h = 1822.5
Since the problem is to find the value of s, the first equation is multiplied by -5 and added to the second equation yielding,
-5·s + 7.5·s = -5·307 + 1822.5
s = 2875 / 25 = 115.

Solution Using Determinants:

Kod:

    |307       1|
    |           |
    |1822.5    5|
s = ------------- = (307·5 - 1·1822.5) / (1·5 - 1·7.5) = -287.5 / (-2.5) = 2875 / 25 = 115.
    |1         1|
    |           |
    |7.5       5|

Book's Solution Based on Trying One of The Choices:

https://i72.servimg.com/u/f72/19/97/10/39/sat24.png