The message
from Joe Smith contains these words:

That is approx the same as what I was saying.

"A typical retail markup is in the order of 50%." I said 50% but I was
referencing that 50% to the retail price.

In your case there would be the 100% wholesale price plus 140% markup.
So the markup is 140/240 = 58% of the retail price.

Mark-up is, as the name implies, added to the cost price. What you
mistakenly call mark-up is normally referred to as (gross) profit
margin.

--
Roger Chapman