The main formula we use is Work=Rate*Time.
The Work is : reading
To find the rate:
Hanna reads 3 pages every 12 minutes, means that the reading rate of Hanna is 3 pages per 12 min, that is 3/12 (pg/min)= 1/4 (pg/min)
the time spent reading p pages is:
Time=Work/Rate= p (pages)/[1/4 (pg/min)]=4p minutes.
thus, m = 4p
Answer: m=4p