Write the expression as a single natural logarithm.

Use the fact that  a*ln(b) =  ln(b^a)

 

2 ln 6 + 3 ln c → ln 6² + ln c³

 

Now use the fact that  ln a + ln b = ln(a*b)

 

2 ln 6 + 3 ln c → ln 6² + ln c³  →  ln 36 + ln c³ → ln(36c³)