Solution -
Let,
CP of 1 camera = 100x
CP of 12 Cameras = 1200x
SP of 12 Cameras = 1200x + 1200x (20/100)
= 1200x + 240x
= 1440x
CP of 8 Cameras = 800x
SP of 8 Cameras = 800x + 800x (10/100)
= 800x + 80x
= 880x
Initial SP of 20 cameras = 1440x + 880x
= 2320x
If he had sold all the 20 cameras at a profit of 15%
CP of 20 cameras = 2000x
Final SP of 20 cameras = 2000x + 2000x (15/100)
= 2000x + 300x
= 2300x
Then,
His profit would have been reduced by Rs. 36.
Intial SP - Final SP = 36
2320x - 2300x = 36
20x = 36
x = 36/20
x = 1.8
So,
The CP of 1 camera = 100x
= 100 × 1.8
= 180
Hence,
The correct answer is option (c) 180.
Thank You