After allowing a discount of 12.5%, the shopkeeper makes a profit of 25% on a bag. At what percent higher than the cost price did he mark the bag? (correct to the nearest integer)

Let's assume the marked price of the bag is 800y.

Discount = 12.5%

Selling price = 800y of (100-12.5)%

= 800y of 87.5%

= 700y

Selling price = (100+25)% of cost price

700y = 125% of cost price

cost price = $$\frac{700y}{125}\times100$$

= $$\frac{700y}{5}\times4$$

= 560y

Marked up percentage = $$\frac{\left(800y-560y\right)}{560y}\times\ 100$$

= $$\frac{240y}{560y}\times100$$

= $$\frac{3}{7}\times100$$

= 42.86%

= 43% (approx.)