I am on the " Sleep Debt Calculator" task at the moment: https://www.codecademy.com/courses/introduction-to-javascript/projects/sleep-debt-calculator

Here is my code so far:

```
const getSleepHours = (day) =>{
if (day === 'monday'){
return 8;
} else if (day === 'tuesday'){
return 3;
} else if (day === 'wednesday'){
return 8;
} else if (day === 'thursday'){
return 4;
} else if (day === 'friday'){
return 8;
} else if (day === 'saturday'){
return 6;
} else if (day === 'sunday'){
return 6;
} else {
return 'Not a day of the week';
}
};
```

I am not sure how to do the step 5. It says: " Inside the `getActualSleepHours()`

function, call the `getSleepHours()`

function for each day of the week. Add the results together and return the sum using an implicit `return`

."

As I understand, the function getSleepHours() is to be on one line because we can use implicit return when the function consist of one line.

But how do we add the results of the function getSleepHours() together if they are strings such as ‘monday’, ‘tuesday’ , etc?

Here is one of my attempts to perform the step: const getActualSleepHours= () => getSleepHours() + 7; It returns NaN.

Did I perform the first steps of the task incorrectly?