Answer: he purchased 5 small file cabinets and 8 large file cabinets.
Step-by-step explanation:
Let x represent the number of small file cabinets that he purchased.
Let y represent the number of large file cabinets that he purchased.
Luis bought 13 new small and large file cabinets. This means that
x + y = 13
Small file cabinets cost $43.50 and large file cabinets cost $65.95. He spent a total of $745.10. This means that
43.5x + 65.95y = 745.1 - - - - - - - -1
Substituting x = 13 - y into equation 1, it becomes
43.5(13 - y) + 65.95y = 745.1
565.5 - 43.5y + 65.95y = 745.1
- 43.5y + 65.95y = 745.1 - 565.5
22.45y = 179.6
y = 179.6/22.45
y = 8
x = 13 - y = 13 - 8
x = 5