Answer:
21 visits
Explanation:
As per statement of the question
Gardener charges a flat fees of $16 per visit.
Then charges for v visits = $ 16v
If his total earnings are d dollars then equation for his total earning will be
16v = d
In a perticular month he earns $ 336
Then equation will be 16v = 336
v =

= 21
Therefore, 21 visits will be the answer.