You can use implemented traits

src/main.rs

@@ -1,5 +1,8 @@
 use hello::math::Point3;
 
 fn main() {
-    let p = Point3::new(0.0, 0.0, 0.0);
+    let p1 = Point3::new(0.0, 0.0, 0.0);
+    let p2 = Point3::new(0.0, 0.0, 0.0);
+
+    let v = p1 - p2;
 }