Answer:
option (B) 20
Step-by-step explanation:
Data provided in the question:
Number of photographs initially sold = 20
selling price of first 20 photographs = $10 each
Therefore,
Revenue from 20 photographs = 20 × $10 = $200
Selling price of further photographs = $15
Let the number of additional photographs sold be 'x'
thus,
total revenue = $200 + $15x
now,
according to the question
80% of ($200 + $15x) = $400
or
0.80 × ($200 + $15x) = $400
or
($200 + $15x) = $500
or
$15x = $300
or
x = 20
Hence,
the answer is option (B) 20