( x + 6 ) + ( x + 11 ) + ...+ ( x + 501 ) = 25450
=> x +6 +x+11+...+x+501=25450
=> 100x + (6+11+...+501) =25450
=> 100x + 25350 =25450
=> 100x = 25450 - 25350 = 100
=> x =1
Vậy x = 1
( x + 4 ) + ( x + 7 )+ ( x + 10 )+ ...+ ( x + 601 ) = 60700
=> x +4 +x+7+ x + 10+...+x+601= 60700
=> 200x + (4+7+10+...+601) = 60700
=> 200x + 60500 = 60700
=> 200x = 60700 - 60500 = 200
=> x =1
Vậy x = 1