$b\text{)}{27}^7>3^{20}$  

${27}^7={\left(3^3\right)}^7=3^{21}$  


$c\text{)}{25}^4<5^{10}$  

${25}^4={\left(5^2\right)}^4=5^8$  


$d\text{)}{125}^3<5^{15}$  

${125}^3={\left(5^3\right)}^3=5^9$  


$e\text{)}{8}^9>2^{25}$  

$8^9={\left(2^3\right)}^9=2^{27}$  


$f\text{)}{100}^7<{10}^{70}$  

${100}^7={\left({10}^2\right)}^7={10}^{14}$  


$g\text{)}{36}^5=6^{10}$  

${36}^5={\left(6^2\right)}^5=6^{10}$  



$h\text{)}{10000}^5={10}^{20}$  

${10000}^5={\left({10}^4\right)}^5={10}^{20}$