1. EXAMPLE 4 Solving an Equation with a Fraction Photography You take 16 of the 24 pictures of a roll of film on your first day of vacation. At this rate, how many days will 4 rolls of film last? SOLUTION Write a verbal model to describe the problem. Let d represent the number of days.

2. EXAMPLE 4 Solving an Equation with a Fraction Write an algebraic model. Divide out common factor. Simplify. = 4 16 24 d = 4 16 24 16 d 4 = 24 16 4 1 1d 1 The multiplicative inverse of 24 16 24 is. = 6d Four rolls of film will last 6 days. ANSWER

3. GUIDED PRACTICE for Example 4 9. What If? In Example 4, suppose you take 20 of the 24 pictures on the first day. At this rate, how many days will 5 rolls of film last? Five rolls of film will last 6 days. ANSWER