Answer:
Jill had $136.50 before buying the book.
Explanation:
Let x be the total amount that Jill had
Then 12% of x is 0.12x
Jill was left with $120.12 after buying the book
Subtracting the cost of book from the total amount will given us the remaining amount.
Which means
![x - 0.12x = 120.12\\0.88x = 120.12\\x = (120.12)/(0.88) \\x = 136.50](https://img.qammunity.org/2022/formulas/mathematics/college/5nx2xtl8a62q4idp2b8jp45oi4rhg201en.png)
Hence,
Jill had $136.50 before buying the book.