To simplify the expression \( a + b + c(d + 2) \), we can distribute \( c \) across the terms inside the parentheses:
\[ c(d + 2) = cd + 2c \]
Now, substituting that back into the original expression gives us:
\[ a + b + cd + 2c \]
So, the equivalent expression is:
a + b + cd + 2c.