Solve the following math problem step by step. The last line of your response should be of the form Answer: \boxed{$Answer} where $Answer is the answer to the problem.

<image>The degree measures of minor arc $\widehat{A C}$ and major arc $\widehat{A D C}$ are $x$ and $y$ respectively. If $m∠ABC = 70°$, find $y$.