we have the function
[tex]g(x)=21\log_2(x+1)+85[/tex]
Part 1
we have that
For g(x)=232 frogs
Find out the value of x
substitute in the given function
[tex]\begin{gathered} 232=21\operatorname{\log}_2(x+1)+85 \\ 232-85=21\log_2(x+1) \\ 147=21\log_2(x+1) \\ \frac{147}{21}=\log_2(x+1) \\ \\ 7=\log_2(x+1) \end{gathered}[/tex]
Apply property of logarithms
[tex]\begin{gathered} 2^7=x+1 \\ x=2^7-1 \\ x=127 \end{gathered}[/tex]
therefore
The answer Part 1 is 127 weeks
Part 2
For x=140 weeks
substitute in the given function g(x)
[tex]\begin{gathered} g(x)=21\operatorname{\log}_2(140+1)+85 \\ g(x)=21\log_2(141)+85 \end{gathered}[/tex]
change the base of the logarithm
Remember that
[tex]\log_2141=\frac{\log_{10}141}{\log_{10}2}=\frac{log141}{log2}[/tex]
substitute
[tex]\begin{gathered} g(x)=21\frac{log141}{log2}+85 \\ \\ g(x)=234.93 \end{gathered}[/tex]
therefore
The answer Part 2 is 235 frogs