The signs are different
Rewrite as
[tex]\frac{3}{8}\text{ x -}\frac{4}{1}[/tex][tex]\text{ }\frac{3}{8}\text{ x - }\frac{4}{1}\text{ = }[/tex][tex]\frac{\frac{3}{8}}{-\frac{1}{4}}\text{ =- }\frac{3\text{ x 4}}{8\text{ x 1}}\text{ =- }\frac{12}{8}\text{ = -}\frac{6}{4}\text{ =- }\frac{3}{2}[/tex]