Hello, we rewrote this log expression:

ln6 - ln15 + ln20

to become

ln(6/15 + 20)

which was simplified to:

ln(2/3 + 4)

and which then:

= ln 8.

The problem is I cant see how the last step occurred eg. ln(2/3 + 4) becoming ln 8.

Thank you for any help in understanding this step.