A dishonest dealer marks up the price of his goods by 20% and gives a discount of 10% to the customer. He also uses a 900 gram weight instead of a 1 kilogram weight. Find his percentage profit due to these maneuvers?

This could be done by a ratio of cp to sp
3 senarios cp:sp
1st 10:12 (20 percent profit)
2nd 10:9 (10 percent discount)
3rd 900:1000 (900 cost selling 1000)
Overall- (10*10*900/12*9*1000)
Simply - cp:sp = 10:12
Now profit 12-10=2
Profit percentage - (2/10)*100=20 percent
So, Answer C- 20 percent

Let cp =1000
Sp=1080
1000=1080, but he sold 900=1080
Then profit 180
P%=180/900*100=20%

Deduction in weight : ( 100*100)/1000 = 10%
Applying multiplying factor concept:
100*(6/5)*(9/10)*(10/9) = 120
So profit = ( 120 - 100 ) = 20%
Solved by : Md.Helal Uddin

let the cost be 100rs per Kg (ie rs.100/1000g)
he sells only 900gms means his real cost is 90rs/900gm
his selling price is 100+20=120-12=108
profit=108-90=18
profit %= 18/90*100=20%answer

900 gm is sold at Rs. 1080..??? Plz explain it...

Profit = (18/90) * 100 ?? Plz explain it.

Let CP = ₹ 1/gram;
Then, he sells 900 g is ₹ 1080;
While the CP of 900 grams is ₹ 900.
% profit = (180*100)/900 = 20%.

Profit = (18/90) * 100 ?? Plz explain it.