Decimal to Fraction I

Suppose that $x = 0.\overline{a_1\dots a_n}$ in base $10$ decimal form, where each $0 \leq a_i \leq 9$. Write $x = a/b$ where $a$ and $b$ are relatively prime integers. Find $a+b$ when $n = 4$ and $a_1a_2a_3a_4 = 1747$.