actually, it is
pages left=total pages-pages read
pages read=(number of pages per hour) times (number of hours)
numbe rof pages per hour=40
x=number of hours
254=total pages
so
y=254-40x, not 4x
what is the question
if it is how many hours to read the book then
0=pages left
0=254-40x
add 40x to both sides
40x=254
divide by 40
x=6.35
6.35 days or aprox 7 days
equation is y=254-40x where y=pages left and x=number of hours read
