Book

Alena read a book at a speed of 15 pages per day. If she read twice as fast, she should read a book four days earlier. How many pages have a book?

Correct answer:

n =  120

Step-by-step explanation:


15 x = n
30 (x-4) = n

15·x = n
30·(x-4) = n

n-15x = 0
n-30x = -120

Row 2 - Row 1 → Row 2
n-15x = 0
-15x = -120


x = -120/-15 = 8
n = 0+15x = 0+15 · 8 = 120

n = 120
x = 8

Our linear equations calculator calculates it.



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