## Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

### Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

# Challenge Task 4 of 4, Implement the Subtract method so that the test passes. Not passing.

Code not passing, some silly mistake cannot find.

Calculator.cs
```public class Calculator
{
public double Result;

public Calculator(double number)
{
Result = number;
}

{
Result += number;
}

public void Substract(double number)
{
Result -= number;
}
}
```
CalculatorTests.cs
```using Xunit;

public class CalculatorTests
{
[Fact]
public void Initialization()
{
var expected = 1.1;
var target = new Calculator(1.1);
Assert.Equal(expected, target.Result, 1);
}

[Fact]
{
var target = new Calculator(1.1);
var expected = 3.3;
Assert.Equal(expected, target.Result, 1);
}

[Fact]
public void BasicSubtract()
{
var target = new Calculator(1.1);
target.Substract(0.2);
var expected = 0.9;
Assert.Equal((); target.Result >= 0.9);
}
}
```

There is a typo in the name of the Subtract method. Other than that, the test should look like this:

```[Fact]
public void BasicSubtract()
{
var target = new Calculator(1.1);
target.Subtract(0.2);
var expected = 0.9;
Assert.Equal(expected, target.Result, 1);
}
```

And don't forget that the same spelling in "calculator.js" will also need to be changed.

Thank you.