a)
[tex]\frac{5^4+5^4+5^4+5^4+5^4}{5^3}=\frac{5*5^4}{5^3}=\frac{5^5}{5^3}=5^2=25[/tex]
b)
[tex]0,25^4*\frac{28^6}{7^6}=0,25^4*4^6=4^{-4}*4^6=4^2=16[/tex]
c)
[tex]\frac{2^6*5^{12}*7^6}{3,5^6}:10^{10}=(2^6*5^{12}*2^6):10^{10}=(2^{12}*5^{12}):10^{10}=10^{12}:10^{10}=10^2=\\100[/tex]
