The value of a book is $150 and decreases at a rate of 4% per year. find the value of the book after 12 years

If it decreases at 4% every year, then its value becomes:

100% - 4% = 96% = 96/100 = 0.96

At the end of the 1 year its value becomes:  150*(0.96)

At the end of the 2 years its value becomes:  150*(0.96)*(0.96) = 150*(0.96)²

At the end of the 3 years its value becomes:  150*(0.96)*(0.96)*(0.96) = 150(0.96)³

So similarly at the end of 12 years, its value becomes 150*(0.96)¹²

=50*(0.96)¹²    simplify with calculator.

≈ 91.91

Value at the end of 12 years becomes ≈ $91.91

I hope this helps.