Tim has 140 paperbacks and hard cover copies in his book shelf. If the hard cover copies do not exceed one sixth the number of paperback copies, what is the minimum number of paperbacks copies in Tim's book shelf?

The minimum number of hard cover copies is 120

Step-by-step explanation:

we have to make two equations, one for the total of copies and the other for the relationship between hard cover copies and paperback copies

x = hard cover

y = paperbacks

x = 1/6 y

x + y = 140

we are going to replace in the second equation the value of x by (1/6 y)

x + y = 140

(1/6 y) + y = 140

7/6 y = 140

y = 140 / (7/6)

y = 120

as a result we obtained the minimum number of paperback copies