Google Analytics - URL Drop-Offs

In GA, I am looking at the landing page (home page) and exit pages for a website I am monitoring with Grafana. I need to be able to subtract the sessions for row 2 from row 1 and then sessions from row 3 from row 2. We are tracking where users are dropping off in the purchase flow.

Right now I have several independent queries but they only show me total sessions not the subtracted amount per row. My code looks like this:

Query A:
SELECT
“exitPagePath” AS metric,
sum(“exits”) as value,
__timeGroupAlias("start-date",__interval)
FROM “”.“report”
WHERE __timeFilter("start-date",__interval) AND “landingPagePath” = ‘.com/’ AND “exitPagePath” = ‘.com/seats.html’
group BY “exitPagePath”, time
ORDER BY metric

Query B:
SELECT
“exitPagePath” AS metric,
sum(“exits”) as value,
__timeGroupAlias("start-date",__interval)
FROM “”.“report”
WHERE __timeFilter("start-date",__interval) AND “landingPagePath” = ‘.com/’ AND “exitPagePath” = ‘.com/checkout.html’
group BY “exitPagePath”, time
ORDER BY metric

Here is the GA Landing Page with secondary dimension - Exit Page: