The mall

Pia spent 1 9/12 hours in her grandparents' house. This time was 8/12 of an hour more than the time she spent at the mall. How much time did she spend at the mall?

Correct answer:

m =  1 ¹⁄₁₂ = 13/12 h

Step-by-step explanation:

$$\begin{gathered} h=1\frac{9}{12}=1+\frac{9}{12}=\frac{1\cdot 12+9}{12}=\frac{12+9}{12}=\frac{21}{12}=\frac{7}{4}=1.75\text{h} \\ h=\frac{8}{12}+m \\ m=h-\frac{8}{12}=\frac{7}{4}-\frac{8}{12}=\frac{21}{12}-\frac{8}{12}=\frac{21-8}{12}=\frac{13}{12}=\frac{13}{12}\text{h}=1\frac{1}{12}\text{h}=1.0833\text{h} \end{gathered}$$

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