38•(21-b)

To simplify the expression \( 38 \cdot (21 - b) \), you can distribute the \( 38 \) to both terms inside the parentheses:

\[ 38 \cdot (21 - b) = 38 \cdot 21 - 38 \cdot b \]

Calculating \( 38 \cdot 21 \):

\[ 38 \cdot 21 = 798 \]

So, the expression becomes:

\[ 798 - 38b \]

Thus, the simplified expression is:

\[ 798 - 38b \]