I have the answer listed below in bold however I dont unders

I have the answer listed below in bold however I dont understand where the 10 mg/ml came from at the beginning of the first equation, can someone explain this in more detail?

A football player’s body was crushed in a collision. The team doctors believe that the player has suffered kidney damage from myoglobin blocking glomerular pores. Tests showed the following results:

plasma creatinine: 3 mg/ml plasma

60 min urine specimen: 120 ml

urine creatinine: 15 mg/ml urine

Question: How much creatinine appears in the urine (in mg/min)? How many mg of creatinine are in the entire urine specimen (i.e. in 120 ml)?

10 mg/ml x 120 ml = 1200 mg 1200 mg/60 min = 20 mg/min

15 mg/ml x 120 ml = 1800 mg 1800 mg/60 min = 30 mg/min

Solution

Answer 2 is correct.

Total urine specimen is 120 ml.

Creatinine value in 1 ml urine = 15 mg

So Total Creatinine value = 15×120= 1800 mg

Now 1800 mg Creatinine appears in 60 min.

So in 1 min creatinine value = 1800/60 = 30 mg/min.