Calculate Black shirts in Unit P

Total shirts for P is 5225 with a ratio of 10:9. Black shirts are $10/19$ of the total.

$\text{Black}_P = \frac{10}{19} \times 5225 = 10 \times 275 = 2750$

Calculate White shirts in Unit U

Total shirts for U is 4950 with a ratio of 11:7. White shirts are $7/18$ of the total.

$\text{White}_U = \frac{7}{18} \times 4950 = 7 \times 275 = 1925$

Calculate the percentage difference

Find how much less $White_{U}$ is than $Black_{P}$ relative to $Black_{P}$.

$\text{Difference} = 2750 - 1925 = 825, \quad \% \text{Less} = \frac{825}{2750} \times 100$

Simplify final result

Performing the final division: $825/2750 = 82.5/275 = 0.3$.

$0.3 \times 100 = 30\%$