You finished washing 3/4 of your windows in an hour and a half. At that rate, how much longer will it take you to finish washing all the windows?

Answer 1

If you finished washing 3/4 of your windows in an hour and a half, then 1/4 of the windows took 90 minutes as well, because 1 - 3/4 = 1/4
This means that each 1/4 of the windows takes 90 minutes because 90 x 4 = <<90*4=360>>360
So it would take you 360 more minutes to finish washing all the windows. Answer: \boxed{360}.