a )( 5^202 + 5 ^ 201 + 5^200 )/31 = 25 ^ 101/ x
5^200 ( 5^2 + 5 ^1 + 5^0 )/31 = 5 ^202/ x
( 25 + 5 +1 )/31 = 5^2/ x
31/31=5^2/ x
1=25/x
x=25
b )( 2^2013 - 2^2012 - 2^2011) / x = 4^1005 / 5
2^2011( 2^2 - 2^1 - 2^0) / x = 2^2010 / 5
2*( 4 - 2 - 1) / x = 1 / 5
2/ x = 1/5
x=10