A section

A section of the boardwalk is made of 15 boards. Each board is 9 1/4 inches wide. The total width of the boardwalk is 144 inches. The spacing between each board is equal. What is the width of the spacing between the boards?

Correct answer:

s =  3/8 inch

Step-by-step explanation:

$$\begin{gathered} a=9\frac{1}{4}=9+\frac{1}{4}=\frac{9\cdot 4+1}{4}=\frac{36+1}{4}=\frac{37}{4}=9.25\text{inch} \\ t=144\text{inch} \\ n=15 \\ x=t-n\cdot a=144-15\cdot \frac{37}{4}=\frac{21}{4}=5.25\text{in} \\ s=\frac{x}{n-1}=\frac{\frac{21}{4}}{15-1}=\frac{3}{8}\text{inch}=0.375\text{inch} \end{gathered}$$

Try another example