Let the cost of making all the stock is 1,

then selling price = 1.3

Half of the stock was sold at original selling price, so sales money on half of the stock is :

1.3*1/2

One quarter of the stock was sold at a discount of 15% of selling price, which means it was sold at 85% of original selling price :

0.85*1.3*1/4

Remaining one quarter of the stock was sold at a discount of 30% of selling price, which means it was sold at 70% of original selling price :

0.7*1.3*1/4

Add them up to get the total sales money :

Total sales money = 1.3*1/2 + 0.85*1.3*1/4 + 0.7*1.3*1/4

= 1.15375

Subtract the cost price 1 from this to get the profit :

Profit = 1.15375 - 1 = 0.15375

Since the cost price is assumed to be unity, the profit is