smc

WLOG, let $x=2$ and $y=5$. From the first sequence, we get $$2,3,4,5$$ so $a_2-a_1=1$ From the second sequence, we get $$2,2+r,2+2r,2+3r,5$$ so $2+4r=5$ and $r=\frac{3}{4}$ Thus, we have $$2,2\frac{3}{4},3\frac{1}{2}...$$ and $b_2-b_1=\frac{3}{4}$ So $\frac{1}{\frac{3}{4}}=\frac{4}{3}$ $$\boxed{\frac{4}{3}}$$