  We give new bounds for $\sum_{{a, m ,n}}\alpha_{m}\beta_n\nu_a {\textrm
e}\left(\frac{a\overline m}{n}\right)$ where $\alpha_{m}$, $\beta_n$ and
$\nu_a$ are arbitrary coefficients, improving upon a result of Duke,
Friedlander and Iwaniec [DFI97]. We also apply these bounds to problems on
representations by determinant equations and on the equidistribution of
solutions to linear equations.
