add a missing colon

1-js/05-data-types/05-array-methods/12-reduce-object/task.md

@@ -4,7 +4,7 @@ importance: 4
 
 # Create keyed object from array
 
-Let's say we received an array of users in the form `{id:..., name:..., age... }`.
+Let's say we received an array of users in the form `{id:..., name:..., age:... }`.
 
 Create a function `groupById(arr)` that creates an object from it, with `id` as the key, and array items as values.