The 3/5 compromise REDUCED the representation of the slave states in Congress. Neither the slaves nor the women had a vote, but they were counted towards the state’s representation in Congress.
Or increased it. It depends on your perspective.
The "free" States wanted not to count slaves AT ALL for the purpose of congressional representation. The "slave" states wanted to count everybody equally (slave or free), with the probable exception of Indians (who nobody wanted to count).
Bingo!
Those who cry the loudest over the 3/5 compromise have no idea what it really was. It actually reduced the national influence of slave states.