## Prealgebra (7th Edition)

$\frac{1}{10}$
The table shows 9 with the B+ blood type and 1 with the B- blood type, so 10 ($9+1$) have type AB. The whole set of blood donors contained 100. $\frac{10}{100}=\frac{10\div10}{100\div10}=\frac{1}{10}$