Answer:
There were 58 hardback books there.
Step-by-step explanation:
This question can be solved using a system of equations.
I am going to say that:
x is the number of paperback books.
y is the number of hardback books.
The number of paperbacks is 12 less than three times the number of hardbacks.
This means that:
[tex]x = 3y - 12[/tex]
Huong had 162 paperbacks.
This means that [tex]x = 162[/tex]
How many hardback books were there?
We want to find y.
So, using the value of x, and the first equation, we have that:
[tex]x = 3y - 12[/tex]
[tex]3y = x + 12[/tex]
[tex]3y = 162 + 12[/tex]
[tex]3y = 174[/tex]
[tex]y = \frac{174}{3}[/tex]
[tex]y = 58[/tex]
There were 58 hardback books there.