i have tried below one, its working fine. I think we have to try to build similar queries in order as mentioned in the left side contents.
select name, round(1.0 * count(distinct order_id) /
count(distinct orders.delivered_to), 2) as reorder_rate
join orders on
orders.id = order_items.order_id
group by 1
order by 2 desc;
Your logic is good, Can you try this?