Given:

Cost price of Earpiece for suman = Rs. 100

Profit % of Suman = 10%

Profit % of Rachna = 20%

Loss % of Deepti = 36.36%

Formula Used:

\({\rm{Selling\;Price}} = \;\frac{{\left( {100{\rm{\;}} + {\rm{\;Profit\;\% }}} \right)}}{{100}}{\rm{\;}} \times {\rm{Cost\;Price\;}}\)

Calculation:

By Ratio Method,

\({\rm{Profit\;\% \;}} = {\rm{\;}}\frac{{{\rm{profit}}}}{{{\rm{Cost\;Price}}}}\)

10% = 1/10 (If C.P. is 10 units and profit is 1 unit then S.P. will be 11 Units)

20% = 1/5

36.36 = 4/11

Now,

\({\rm{Suman}} \times {\rm{\;}}\frac{{{\rm{S}}.{\rm{P}}.1}}{{{\rm{C}}.{\rm{P}}.1}}{\rm{\;}} \times \frac{{{\rm{S}}.{\rm{P}}.2}}{{{\rm{C}}.{\rm{P}}.2}}{\rm{\;}} \times {\rm{\;}}\frac{{{\rm{S}}.{\rm{P}}.3}}{{{\rm{C}}.{\rm{P}}.3}} = {\rm{New\;C}}.{\rm{P}}.{\rm{\;of\;Suman}}\)

 The Original C.P. of Suman is ‘Rs. 100’

New C.P. of Suman

⇒ \(100 \times {\rm{\;}}\frac{{11 \times 6 \times 7}}{{10 \times 5 \times 11}} = {\rm{Rs\;}}84\)

 Profit of Suman = (Original C.P. – New C.P.)

⇒ (100 - 84) = Rs.16

Profit of Suman in First Transaction 

⇒ \(\frac{{10}}{{100}}\; \times 100 = 10\)

Total Profit of Suman

⇒ (Rs. 16 + Rs. 10) = Rs. 26

∴ Total Profit earned by Suman is Rs. 26.