A man sells one camera A for Tk. 7500 at a gain of 20% and another camera B for Tk. 8550 at a loss of 5%. Find his total loss or gain%.

Here,
we just know the selling price and the gain and loss incurred, on two cameras.
Therefore,
first calculate the cost price of both the cameras, because gain or loss is calculated on the cost price of the material.
When a shopkeeper earns profit, Cost Price = 100/(100 + Gain%) × S.P.
When shopkeeper incurs a loss, Cost Price = 100/(100 – Loss%) × S.P.

C.P. of camera A = 100/(100 +20) × 7500
= 100/120 × 7500
= Tk. 6250
C.P of camera B = 100/(100 – 5) × 8550
= 100/95 × 8550
= Tk. 9000

Total C.P. = Cost of camera A + Cost of camera B
Total C.P. = 6250 + 9000 = Tk. 15250
Total S.P. = 7500 + 8550 = Tk. 16050
Selling Price > Cost Price, hence man gains during this transaction.

Gain = S.P. – C.P.
= 16050 – 15250
= Tk. 800
Gain% = Gain/C.P. × 100
Gain% = 800/15250 × 100
= 5.24%