Official Explanation
The correct answers are 90 fabrics that are both heavy duty and waterproofed, and 260 fabrics that are either heavy duty or waterproofed.
There are 250 heavy-duty fabrics and 100 fabrics that are waterproofed. If all of the waterproofed fabrics were also heavy duty, there would be 100 fabrics that are both heavy duty and waterproofed. This is the largest number of fabrics that could possibly be both heavy duty and waterproofed. The number 100 is not listed in the table, however, and 150 is too large. So of the numbers listed in the table, the largest number of Turner fabrics that could possibly be both heavy duty and waterproofed is 90.
The total number of fabrics that are either heavy duty or waterproofed is 250 + 100, or 350. The largest number listed in the table is 375, but this number exceeds 350. The next largest number is 260. Of the numbers listed in the table, the largest number of fabrics that could possibly be either heavy duty or waterproofed is 260.