-π/8-(-4π/8)
Thanks Zegroes,
A slightly better answer would be
$$\frac{-\pi}{8}-\frac{-4\pi}{8}\\\\ =\frac{-\pi}{8}+\frac{4\pi}{8}\\\\\ =\frac{-\pi+4\pi}{8}\\\\ =\frac{3\pi}{8}$$
Those signs are pi?If so then do -3.14/8-(-4*3.14/8) in the calculator and you should get 1.1775