# What will be the Cost Price of Mobile Set? If

The total cost price of two mobile set is Rs.13600 and their selling prices are equal. If one of the two mobile set is sold at a loss of 12% and another is sold at a loss of 18%, then the cost price of the mobile set which is sold at a loss of 18% is:

1. Rs. 7040
2. Rs. 6840
3. Rs. 7740
4. None of these

Explanation:-
The total cost price of two mobile set = Rs.13600
Let the cost price of a mobile  = X
Then, the cost price of other mobile = 13600 – X

If one mobile set is sold at a loss of 12 %,
Then, the selling price of the mobile = X – X x 12/100
= X – 3 X/25
= (25 X – 3 X)/25
= 22 X/25

If another mobile set is sold at loss of 18 %.
Then, the selling price of another mobile = (13600 – X) – (13600 – X) x 18/100
= 13600 – X  – (13600 – X) x 9/50
= 13600 – X  – 13600 x 9/50 – 9 X/50
= 13600 – X – 2448  – 9 X/50
= 11152 – (X + 9 X/50)
= 11152 – (50 X + 9 X )/50
= 11152 – 59 X/50

Selling price of both are equal.
Then, 22 X /25  = 11152 – 59 X/50
22 X/25 + 59 X/50 = 11152
(44 X + 59 X )/50 = 11152
103 X /50 = 11152
103 X = 11152 x 50
X = 11152 x 50/103
X = 5413.59

The cost price of the mobile set which is sold at a loss of 18% = 13600 – 5413.59
= Rs.8136.41