Boxes to mail

Leah has six boxes that she wants to mail. Five identical boxes weigh 3 and 7/8 pounds each. The last box weighs two times as much as one of the other packages. How many pounds do all six boxes weigh?

Correct answer:

m =  27 ¹⁄₈ = 217/8 lb

Step-by-step explanation:

$$\begin{gathered} a=3\frac{7}{8}=3+\frac{7}{8}=\frac{3\cdot 8+7}{8}=\frac{24+7}{8}=\frac{31}{8}=3.875\text{lb} \\ b=2\cdot a=2\cdot \frac{31}{8}=\frac{2\cdot 31}{8}=\frac{62}{8}=\frac{31}{4}=7.75\text{lb} \\ m=5\cdot a+b=5\cdot \frac{31}{8}+\frac{31}{4}=\frac{217}{8}\text{lb}=27\frac{1}{8}\text{lb}=27.125\text{lb} \end{gathered}$$

Try another example