To simplify the expression, we need to operate the like terms, the like terms are whose variables and exponents are the same.
[tex]15+(-5)-\frac{4}{5}j-\frac{2}{5}j+7[/tex][tex]15-5-\frac{4}{5}j-\frac{2}{5}j+7[/tex][tex]15-5+7-\frac{4}{5}j-\frac{2}{5}j[/tex]Add and subtract, so the simplify is:
[tex]17-\frac{6}{5}j[/tex]