if you mean
[tex]log_5(15)=x+3[/tex]
remember
[tex]log_a(b)=c[/tex] translates to [tex]a^c=b[/tex] so
[tex]log_5(15)=x+3[/tex] translates to [tex]5^{x+3}=15[/tex] which is equal to
[tex](5^x)(5^{3})=15[/tex]
[tex](5^x)(125)=15 [/tex]
divide both sides by 125
[tex]5^x= \frac{3}{25} [/tex]
take the ln of both sides
[tex]ln(5^x)= ln(\frac{3}{25}) [/tex]
[tex]xln(5)= ln (\frac{3}{25}) [/tex]
divide both sides by ln(5)
x=ln(3/25)/ln(5)
use calculator to evaluate
x≈-1.31739
the aproximate value is -1.32 to the hundreth
