Question

The value of x is negative. What must be true about 10 - x? Explain.

Answer 1

What must be true is the expression will actually be adding 10 + (+ x), because of the two marks you have to make when subtracting by a negative.

The subtraction sign is also the negative sign. So in this case, the expression is also saying -x, which means there is two negative signs.

A double negative is a positive, so in this case the x will be turned to a positive integer.

If this is still too confusing, she can plug in a number to replace x. Let’s try it with -2:

Ex. 10 - (-2)= 12.

The two negative signs turn into one positive sign, AKA an addition sign. So, the above expression can be simplified as 10 + 2, or 12.