Answer:
Proofreading this, it would be:
I have been with my current employer for five years; I am responsible for: planning development.
Step-by-step explanation:
Colons (:) are used in sentences to show something is following, like a quotation, an example, or a list
while semicolons (;) are used to join two independent clauses or two complete thoughts that could stand alone as complete sentences.
in the above sentence:
"I have been with been with my current employer for five years" is an independent clause and we can use a semicolon to join this with another independent sentence "I am responsible for planning development"
While "For planning development " is giving more information about what the speaker is responsible for, We can use the colon to identify or list what the speaker is responsible for.