Question

Check that a - b is not = b - a when a = -9/11 and b = -4/11

Answer 1

$a-b=-\frac{9}{11}--\frac{4}{11}  \\=-\frac{9}{11}+\frac{4}{11} \\=-5/11$

whereas

$b-a=-\frac{4}{11}--\frac{9}{11} \\=-\frac{4}{11}+\frac{9}{11}\\=5/11$