|-18| + |+3|

To solve the expression \( |-18| + |+3| \), we first need to calculate the absolute values.

1. The absolute value of \(-18\) is \(18\), so \( |-18| = 18 \).
2. The absolute value of \(+3\) is \(3\), so \( |+3| = 3 \).

Now we can add these results together:

\[ 18 + 3 = 21 \]

Therefore, \( |-18| + |+3| = 21 \).