A dealer sells goods at 4% loss on cost price but he uses 28 g instead of 32 g. What is his per cent profit or loss?

Given that, a = 4%, b = 28 g and c = 32 g
Required profit = [(100 - a) x (c/b) -100] %
=[(100 - 4) x (32/28) - 100] %
= [96 x (32/28) - 100]%
= [(96 x 8)/7 - 100]%
= (768 - 700)/7 %
= 68/7 %
= 9⁵/₇ % gain
+ ve sign shows that profit is earned here.