When $N$ is divided by $10$, the remainder is $a$. When $N$ is divided by $17$, the remainder is $b$. What is $N$ modulo $170$, in terms of

When $N$ is divided by 10, the remainder is $a$. When $N$ is divided by 17, the remainder is $b$. What is $N$ modulo 170, in terms of $a$ and $b$?  (Your answer should be in the form $ra+sb$, where $r$ and $s$ are replaced by nonnegative integers less than 170.)