Fiona spent $$1$$ h $45$ min at the library. At the library, she spent $$30$$ min looking for reading materials. She spent the rest of the time reading them. How many minutes did Fiona spend reading? (adapted from 2011 Math kangaroo Problems, Level 3-4 , Question \#4) 
Overseas Competition->Knowledge Point->Counting Modules->Permutations and Combinations->Combinations
Time spent reading  $$\rm =1h45min-30min$$  $$\rm =1h15min$$  $$\rm =60min+ 15min$$  $$\rm =75min$$. 