Hey there!
To start, first set up a proportion where x is the cost to make 27 copies:
27/x=150/4.50
Now, solve for x by cross multiplying which should look like this:
27*4.50=x*150
Now simplify and solve for x:
121.5=150x
x=0.81
Therefore, it costs $0.81 to make 27 copies.
Hope this helps!