I want to have a question that asks students whether an ordered triple satisfies a plane’s equation. I know that I need to have three different math inputs since Desmos only recognizes ordered pairs, and that’s fine - I have three inputs called ans_x, ans_y, and ans_z.

I can’t seem to get the right syntax to evaluate the function. For the purposes of this question, let’s say that the equation of the plane is 2x+y+z=1.

I *think* I want to use something like simpleFunction. Here’s the relevant snippet:

```
plane = simpleFunction("2a+b+c", "a", "b", "c")
checkValue = plane.evaluateAt(ans_x.numericValue,ans_y.numericValue,ans_z.numericValue)
when checkValue = 1 "Correct!"
otherwise "Incorrect"
```