Update activity.md

Author: amelinagzz

Lessons/09-Functional-ProgrammingPt.1/assignments/activity.md

@@ -19,8 +19,6 @@ func doubleIt(inputArray: Array<Int>) {
 doubleIt(inputArray: [1,2,3]) // [2,4,6]
 ```
 
-**TODO:**
-
 Code the declarative (FP) version of `doubleIt`so that it achieves the same result as the code above by using the `map` function instead of the `for loop`
 
 <!--
@@ -38,11 +36,11 @@ doubleIt(inputArray: [1,2,3]) // [2,4,6]
 
 2. Suppose we have an array containing strings representing the contents of a directory:
 
-let exampleFiles = ["README.md", "HelloWorld.swift", "FlappyBird.swift"]
+`let exampleFiles = ["README.md", "HelloWorld.swift", "FlappyBird.swift"]`
 
-Now suppose we want an array of all the .swift files. This is easy to compute with a simple loop. Use the HOF filter.
+Now suppose we want an array of all the .swift files. This is easy to compute with a simple loop. Use the HOF `filter`.
 
-3. Define a function that sums all the integers in an array.
+3. Define a function that sums all the integers in an array. Use `reduce`
 
 4. Suppose we have the following struct, consisting of a city’s name and population (measured in thousands of inhabitants):