Let us consider the cost price of article be Rs x
The Profit percent is = 25% of 100 = 25/100
Selling price of article = x + x × 25/100
= x + x/4
= (4x+x)/4
= Rs 5x/4
If cost price of article is 20% less (given) = 20% of 100 = 20/100
Now, cost price is = x – x×20/100
= x – x/5
= (5x-x)/5
= Rs 4x/5
Now, selling price is = Rs5x/4 – 36.75
The Profit percent is = 30% of 100 = 30/100
He would have gained 30% selling at that price (Given)
We know that, Gain = SP – CP
= 5x/4 – 36.75 – 4x/5
= (25x – 16x)/20 – 36.75
= 9x/20 – 36.75
Gain % = (gain/cost price) × 100
30% = [{(5x/4) – 36.75} – (4x/5)] / (4x/5) × 100
30/100 = (9x/20 – 36.75) / (4x/5) × 100
x = 175
∴ Cost price of article is Rs 175.