Answer: £4
Explanation:
From the question, we are informed that when the normal price of a book is reduced by 30%, then the sale price of the book is £2.80.
Since the normal price of a book is reduced by 30%, that means the book is sold at (100% - 30%) = 70% of its normal price.
Let the normal price of the book be y.
70% of y = £2.80
70/100 × y = £2.80
0.7 × y = £2.80
0.7y = £2.80
y = £2.80/0.7
y = £4
The normal price of the book is £4.