Look at it this way.
Let s = #scrapers
Let w= #washers
Total items = 6
(1) s + w = 6
Let 0.99w = total cost of washers
Let 0.69s = total cost of scrapers
Difference in cost of washers and scrapers = 2.58
(2) 0.99w - 0.69s = 2.58
Here are your two systems of equations:
s + w = 6
0.99w - 0.69s = 2.58
You can use the substitution method to find how many of each were purchased.
Can you take it from here?