Let x be the total number of people who could have voted. We know that 4/25 didn't vote, so the actual number of people who voted is the remaining 21/25 of x.
Out of these people, 4/7 voted for the winner:
[tex]\dfrac{21}{25}x\cdot\dfrac{4}{7}=\dfrac{12}{25}x[/tex]
We know that this fraction resulted in 4956 votes, solving for x we have
[tex]x=\dfrac{4956\cdot 25}{12}=10325[/tex]
So, 10325 people could have voted. But we know that 4/25 didn't vote, while the remaining 21/25 did. So, the number of voters who took part to the election is
[tex]10325\cdot 21/25=8673[/tex]
Just for checking, we have indeed
[tex]8673\cdot \dfrac{4}{7}=4956[/tex]
which confirms the result.
