1 files changed, 7 insertions, 2 deletions
diff --git a/rustlings/solutions/01_variables/variables4.rs b/rustlings/solutions/01_variables/variables4.rs
index dcf2377..7de6bcb 100644
--- a/rustlings/solutions/01_variables/variables4.rs
+++ b/rustlings/solutions/01_variables/variables4.rs
@@ -1,4 +1,9 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
-    // It will be automatically filled after you finish the exercise.
+    // In Rust, variables are immutable by default.
+    // Adding the `mut` keyword after `let` makes the declared variable mutable.
+    let mut x = 3;
+    println!("Number {x}");
+
+    x = 5;
+    println!("Number {x}");
 }