Chapter 1, Equations and Inequalities - 1.3 Solve Linear Equations - 1.3 Exercises - Problem Solving - Page 24: 77

Answer B

Let x = time working together One writes 7 names in 6 minutes: $\frac{7}{6}x$ Another writes 17 names in 10 minutes $\frac{17}{10}x$ The third writes 23 names in 15 minutes: $\frac{23}{15}x$ If they work together: $\frac{7}{6}x+\frac{17}{10}x+\frac{23}{15}x=440$ $\frac{35x+51x+46x}{30}=440$ $35x+51x+46x=13200$ $132x=13200$ $x=100$ The correct answer is B.