# Plus and Minus explainer

#1

The aim of this puzzle: To add to and subtract from the variable `z`
Walkthrough of the solution: This puzzle demonstrates how the plus (`+`) and minus (`-`) operators can be used to update a variables value. In the initial code the number 0 is being added to `z`, and then subtracted from `z`. To solve this puzzle, change 0 to be a number `1` or greater.
Sample code solution:
(Tap below to reveal)

``````var z = 5;
z = z + 5;
print('z is ' + z);
z = z - 3;
print('z is now ' + z);
``````

JavaScript Concepts: Binary Expression (=, +, -), Calling Functions, Identifiers, Variable Declaration
Grasshopper Concepts: print()

#3

This makes no sense to me

#4

To solve the puzzle, there are 2 things you need to change:

1. Edit the 1st number `0` into a larger number, like `5`
2. Edit the 2nd number `0` into a larger number, like `3`

That will turn your code into the solution code:

``````var z = 5;
z = z + 5;
print('z is ' + z);
z = z - 3;
print('z is now ' + z);
``````

Iâ€™ll explain what each line does.

`var z = 5;`
â€śCreate a variable (a thing to store data) called `z` and store the number `5` in it.â€ť

`z = z + 5;`
â€śChange the value of `z` into `z + 5`. Since `z` was storing `5`, this becomes `10`.â€ť

`print('z is ' + z);`
"Output the text `'z is 10'` since the value of `z` is now `10`"

`z = z - 3;`
â€śChange the value of `z` into `z - 3`. Since `z` was storing `10`, this becomes `7`.â€ť

`print('z is now ' + z);`
"Output the text `'z is 7'` since the value of `z` is now `7`"

â€“Frankie

#5

I have tried to enter the code as per your instructions in the exercise, but I am now convinced that the code is ironically incorrectly coded, thus making it impossible to solve. How do I complete the exercise when it is incorrectly coded and impossible to solve?

#6

Can you post a screenshot of your code?

â€“Frankie

#7

Me eitherâ€¦Iâ€™m so confused by this

#8

Hey there, hope I can help. Take a look at @Grasshopper_Frankieâ€™s great explanation above. Just in case that doesnâ€™t clarify things, I will also walk through the solution code line by line:

``````var z = 5
``````

This creates a variable named `z` and gives it the value `5`.

``````z = z + 5
``````

This line says â€śTake the value of `z`, add `5` to it, and then assign that new value to `z`.â€ť Because `z` is `5`, this is the same as writing `z = 5 + 5`.

Another way to phrase this is "`z` is equal to whatever value `z` has now, plus 5."

`z` will now have the value `10`

``````print('z is ' + z)
``````

Because `z` now has the value `10`, this will print `'z is 10'`

``````z = z - 3
``````

This line says â€śTake the value of `z`, subtract `3` from it, and then assign that new value to `z`.â€ť Because `z` is `10`, this is the same as writing `z = 10 - 3`.

``````print('z is now ' + z)
``````

Because `z` now has the value `7`, this will print `'z is 7'`

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