I need help setting up an inequality word problem

Question

I cannot set this up as a two-step inequality -

The rule of thumb in filmmaking is that you shoot at least 3 min. of film for every minute in a films final cut. A 30-min roll of film costs $250. How much will film cost to make a 90-min movie? 

Answer 1

$250 for a 30 minute roll of film. If you get 1 minute of final cut for 3 minutes of footage, then you can get 10 minutes of final cut per 30 minutes on the roll of film. So you'd need 9 rolls of film to get your 90 minute movie. 9 x 250 = $2250