Question 1125415

I would be grateful for help breaking this down.  Thank you.

One day a store sold 33 sweatshirts. White ones cost​ $9.95 and yellow ones cost $13.50. In​ all, ​$374.50 worth of sweatshirts were sold. How many of each color were​ sold?
The store sold 
___ white sweatshirts.
<pre>Let number of white sold, be W
Then number of yellow sold = 33 - W
We then get: 9.95W + 13.5(33 - W) = 374.5
9.95W + 445.5 - 13.5W = 374.5
9.95W - 13.5W = 374.5 - 445.5
- 3.55W = - 71
W, or white sold = {{{highlight_green(matrix(1,3, (- 71)/(- 3.55), "=", 20))}}}
Number of yellow sold = {{{highlight_green(matrix(1,3, 33 - 20, "=", 13))}}}