word problems

Question

An online site sells used paperback for $1 each and hardcover books for $4 each. If on a given day the site generates $155 in sales by selling thirty more paperbacks than hardcover books, how many of each type of book are sold?

Answer 1

Revenue = $1(#paperbacks) + $4(#hardbacks)

 

Let p = # paperbacks sold

Let h = # hardbacks sold

 

30 more paperbacks were sold than hardbacks:

p = h + 30

 

1(h+30) + 4h = 155

 

5h + 30 = 155

5h = 125

h = 25 hardbacks sold

h+30 = 55 paperbacks sold

 

Check:  1(55) + 4(25) = 55 + 100 = $155