We are told that the actual size of the book is 7.5 inches wide whilst on the computer monitor, it looks 2.5 inches wide. This means that on the monitor, every "real" 7.5 inches is scaled down to 2.5 inches; therefore, one inch of on the monitor will be
[tex]\frac{7.5in}{2.5in}=3[/tex]Hence the scale being used is
3 real inches = 1 monitor inch.
