Question

A mobile phone is sold for rs 3120 at a loss of 4% what will be the gain or loss % if it is sold for rs 3640

Answer 1

Let x be original prize of mobile phone..
Hence,
$x - \frac{4x}{100} = 3120 \\ \frac{96x}{100} = 3120 \\ x = 3250$
Profit=3640-3250=390
% profit =100×390÷3250=12%
12% of gain is obtained