Book

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

Result

n =  120

Solution:


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

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

n = 120
x = 8

Calculated by our linear equations calculator.


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