Hello!
Answer:
The cost of the book is $150.
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Step-by-step explanation:
CP =
![(SP(100))/(100 + PP)](https://img.qammunity.org/2021/formulas/mathematics/high-school/5ijato75xyxme9yj4vwravfio0i64xant1.png)
Basically, what this formula is saying is that to find the cost price (CP), we must multiply the sale price (SP) by 100, and divide the product by the sum of 100 + profit percentage (PP).
CP =
![(180(100))/(100 + 20)](https://img.qammunity.org/2021/formulas/mathematics/high-school/vyp9g8u07dnk7dqihc4qbhp1o6s2znbzt2.png)
CP =
![(18000)/(120)](https://img.qammunity.org/2021/formulas/mathematics/high-school/kkf3t9jz6pehog0l1mm2ry5vyvrmbyr7ny.png)
CP = 150