Chapter 6 - Percent - 6.4 Using Proportions to Solve Percent Problems - 6.4 Exercises - Page 422: 69

231 used some other method of payment.

If 85% used PayPal, 100-85=15% used some other form of payment. The whole is 1540. The percent is 15%. The part is unknown. $\frac{x}{1540} = \frac{15}{100}$ $100x = 1540\times15$ $\frac{100x}{100} = \frac{23100}{100}$ $x = 231$