Sooner 24191

If I read a book at a rate of 15 pages a day, I will read it three days sooner than if I read it at a rate of 10 pages a day. If I read at a rate of 6 pages daily, I'll read a book.

Correct answer:

x =  15 d

Step-by-step explanation:

$$\begin{gathered} 15(d-3)=n \\ 10\cdot d=n \\ 15\cdot (d-3)=n \\ 10\cdot d=n \\ 15d-n=45 \\ 10d-n=0 \\ Row2-\frac{10}{15}\cdot Row1\to Row2 \\ 15d-n=45 \\ -0.33n=-30 \\ n=\frac{-30}{-0.33333333}=90 \\ d=\frac{45+n}{15}=\frac{45+90}{15}=9 \\ d=9 \\ n=90 \\ x=n/6=90/6=15\text{d} \end{gathered}$$

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