Answer:
Rs. 18000
Step-by-step explanation:
[tex]x(1 + 25\%) \: (1 - 15\%) - x = 900[/tex]
[tex]1.0625x - x = 900[/tex]
[tex]0.0625x = 900[/tex]
[tex]x = 14400[/tex]
•••••
[tex]14400 \times (1 + 25\%)[/tex]
[tex] \: \: \: \: \: \: \: \: = 14400 \times 1.25[/tex]
[tex] \: \: \: \: \: \: \: \: =Rs. 18000[/tex]
The marked price of a calculator is [tex]\boxed{\green{Rs. 18000}}[/tex]