Simplifying negatives doesn't account for negative coefficients

[phet-steele]

1. Make a setup on the Variables screen with the following conditions:

• Create expression: 1 + (-x)
• With the Values panel, set x = -1

The total will read "2" (correct, 1 + (-(-1) = 2)

2. Enable the checkboxes for "all coefficients". The expression will now read: 1 + (-1x)
3. Enable the checkbox "simplify negatives" (what's it called now?). You will now totally change the equation (bad) but not affect the total (good):

Just from reading the above equation, 1 - (-1(-1)) should equal 0, not two. Enabling "variable values" shows that either way you cut this equation, the total should be 0:

To be clear, the problem is not that the total remains as 2, but that simplifying negatives in this situation does not properly remove the negative from the "-1" coefficient.

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[amanda-phet]

To further clarify the correct behavior, after step 3 above the expression should be 1 – 1x.

[jbphet]

This should now be fixed. Assigning to @phet-steele to verify on master.

[phet-steele]

@jbphet this has been fixed for....awhile. Closing!