diff --git a/1-js/09-classes/02-class-inheritance/article.md b/1-js/09-classes/02-class-inheritance/article.md
index a6970b4bc4..f6a7c67ae4 100644
--- a/1-js/09-classes/02-class-inheritance/article.md
+++ b/1-js/09-classes/02-class-inheritance/article.md
@@ -11,7 +11,7 @@ class Animal {
     this.name = name;
   }
   run(speed) {
-    this.speed += speed;
+    this.speed = speed;
     alert(`${this.name} бежит со скоростью ${this.speed}.`);
   }
   stop() {
@@ -57,7 +57,7 @@ class Animal {
     this.name = name;
   }
   run(speed) {
-    this.speed += speed;
+    this.speed = speed;
     alert(`${this.name} бежит со скоростью ${this.speed}.`);
   }
   stop() {
@@ -144,7 +144,7 @@ class Animal {
   }
 
   run(speed) {
-    this.speed += speed;
+    this.speed = speed;
     alert(`${this.name} бежит со скоростью ${this.speed}.`);
   }