DIVIDE 45 minutes in the ratio 4:5?

We are essentially dividing 45 minutes into 9 parts....and each part = 5 minutes

So .......  4 parts x 5 min = 20 min

And....... 5 parts x 5 min  = 25 min  

So.....the ratio   =

20 min  :   25 min

4 x5 is 20

5 x5 is 25

so it is 

20 : 25

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