Chapter 7 - Section 7.6 - Percent and Problem Solving: Interest - Exercise Set - Page 518: 10

150 dollars

I=PRT Let P=1000dollars , R=10% ,T = 18 months 18 months =$\frac{18}{12}$year=$\frac{3}{2}$ I=1000 $\times$10% $\times$ $\frac{3}{2}$ Write 10% as a decimal I = 1000$\times$0.10$\times$ $\frac{3}{2}$ Multiply I= 100$\times$$\frac{3}{2}$ = $\frac{300}{2}$ =150 The simple interest is 150 dollars.