Mr. R.’s World of Math

The voice they heard whispering sounded familiar. It was Suzy’s voice.
“No dogs or cats ate me. I’m right up here. Now help me before Mr. Geebrah comes back.”
They looked up and saw Suzy. She was sticking her head through the iron bars of a steel door. The door was built into the wall above the two cages.
“It’s me guys. I’m stuck in this tiny room- help me get out!” Suzy pleaded.
“Just hold on,” yelled Jake, “We’ll get you out of there.”
Jake and Jenna helped Joe climb on top of Numer’s cage. When he was on top he saw the door of Suzy’s room had three locks on it!!!
“I don’t know how we’re gonna’ unlock these three locks,” said Joe, “These are the strangest locks I’ve ever seen. They all have fractions on them. There’s one with 4/6 one with 45/108 and one with 134/208 on it.”

“Where are we gonna’ find the keys for those?” asked Jake.
“I don’t know, but hurry,” cried Suzy, “Mr. Geebrah’s told me he’s coming back soon and then I would pay for failing my math test!”
Mr. Geebrah was actually on his way back to his castle! It takes him 3/4 of an hour to get there, and already a 1/2 hour had passed. How many more minutes would it be before Mr. Geebrah got to the castle?