# TIaO - Part 4

Jeremy can control the flow of water in the inlets of a specific tank. The tank has $$2$$ inlets. The first inlet can fill the tank in $$4$$ hours. The second inlet can fill the tank in $$12$$ hours.

He controlled the flow by the following steps:

• First, he made the first inlet flow.
• When the tank was filled by $$\frac{1}{4}$$ by the first inlet, he turned off the first inlet and turned on the second inlet.
• When the tank was filled by $$\frac{1}{4}$$ by the second inlet, he turned off the second inlet and simultaneously turned both inlets on.
• Finally, when the tank was full, he closed both inlets.

From the time he made the first inlet flow, how many hours did it take him to fill the tank?

×