Linear Congruences with Ratios

We use new bounds of double exponential sums with ratios of integers from prescribed intervals to get an asymptotic formula for the number of solutions to congruences $$\sum _{j=1}^n{a}_j{x}_j{y}_j^{-1}\equiv a_0(\mathrm{m}\mathrm{o}\mathrm{d}p),$$ with variables from rather general sets.