In an election between two candidates, one got 55% of the total valid votes, 20% of the votes were invalid. If the total number of votes was 7500, the number of valid votes that the other candidate got, was :

Total number of votes = 7500 

Given that 20% of Percentage votes were invalid

 => Valid votes = 80%

 Total valid votes = 7500*(80/100) 

1st candidate got 55% of the total valid votes. 

Hence the 2nd candidate should have got 45% of the total valid votes 

=> Valid votes that 2nd candidate got = total valid votes x (45/100) 

7500*(80/100)*(45/100) = 2700