# Need clarification on 6. return II example

#1

Could anyone explain to me how the function multiplyByNineFifths(celsius) understands to use the 15 degrees argument from the Fahrenheit function? At no point is there any line with multiplyByNineFifths(15).

I can't wrap my head around the steps the program takes in this example. How does the argument of one function apply to the other?

``````function multiplyByNineFifths(celsius) {
return celsius * (9/5);
}

function getFahrenheit(celsius) {
return multiplyByNineFifths(celsius) + 32;
}

console.log('The temperature is ' + getFahrenheit(15) + '°F');
// Output: The temperature is 59°F``````

#2

This function header has a parameter, `celsius` ...

``function getFahrenheit(celsius)``

When you make this call ...

``console.log('The temperature is ' + getFahrenheit(15) + '°F');``

... that `15` between the parentheses gets assigned to the parameter `celsius` of the `getFahrenheit` function.

Then, inside that function we have this ...

``return multiplyByNineFifths(celsius) + 32;``

That variable, `celsius`, is the same variable as the parameter, `celsius`, and therefore has the value `15`. That is how the value of `15` gets passed to the `multiplyByNineFifths` function.

This gets the result evaluated and `return`ed back to the `getFahrenheit` function where it called the `multiplyByNineFifths` function ...

``return celsius * (9/5);``

#3

Thank you for the reply, I can see the steps a lot more clearly now. Had to step back for a day to read this with a clear mind. Much appreciated!

#4