Suppose that ln2=a and ln5=b. Use properties of logarithms to write each log in terms of a and b. -> ln20

ln a + ln a + ln b = 

ln 2 + ln2 +  ln5  =

ln (2 * 2) + ln 5 =

ln4 + ln 5  =

ln (4 * 5)  =

ln 20 = ln (2 * 2 * 5)  = ln (a * a * b)