Two articles are sold for Rs.840 and Rs.960 at 20% gain and 4% loss respectively. What is the overall gain or loss percent?

1st article :

SP1 = 840

P1 = 20%

CP1 = $$ 840 \times \frac{100}{120} = 700 $$

2nd article :

SP2 = 960

L2 = 4%

CP2 = $$ 960 \times \frac{100}{96} = 1000 $$

total SP = SP1 + SP2

           = 840 + 960 

            = 1800

total CP = CP1 + CP2

             = 700 + 1000

            = 1700

gain % = $$ \frac{SP - CP}{CP} \times 100 $$

              = $$ \frac{1800 - 1700}{1800} \times 100 $$

              = $$ 5 \frac{15}{17} $$ % gain