This is an example of a different problem: These kinds of questions" involve what's called "unit rate" or involve "proportions." In either case, the units are extremely important.
"32 copies per minute" is a unit rate. That is, "how many of these for one of those?"
In this problem, "per" means division. There are 60 seconds per minute, so this is:
(32 copies) / (60 seconds)
The question asks, "How many copies does it make in 3 minutes and 45 seconds?"
Note that (copies/minute)*minute results in copies because the minutes cancel out. So,
( (32 copies) / (60 seconds) ) * ( 225 seconds) = 120 copies
This can also be set up as a proportion (because the same rate is assumed).
Let x = number of copies
32/60 copies/second = x / (225 seconds)
x = ((32 copies) / (60 seconds))*(225 seconds) [cross-multiply]
x = 120 copie
