Answer :
Given :-
- Cost of school exercise book was Rs. 10
- Now , she had to pay Rs. 12 for it .
To Find :-
- The increase percentage of price of that book .
Solution :-
[tex]\underline{\bf{\dag} \:\bold{As\;we\;know\: that\: :}}[/tex]
[tex]\sf Increase \% = \dfrac{(Value\;Increased)}{Initial\; Value} \times 100 \%[/tex]
According to the question,
→ Increase of Price = ( Rs. 12 - Rs. 10 )
⇒ Rs. 2
→ Initial Value = Rs. 10
Let's solve by putting the values in the formula !
[tex]\sf \leadsto \dfrac{2}{10} \times 100 \%[/tex]
⇝2×10%
⇝20%
∴ The percent of increase in price of that school exercise book is 20 %