hey can someone tune me a slot port???

i want to keep it 3 inches away from side wall and back wall

box dimensions are as follows W:24 H:15 D: 18.57
this box is a 3 cu ft box with out sub displacement...3/4 mdf board

port width will be 3 inches and 13.5? inches long?

i want to tune to 32 hz...can someoen calculate this for me...i did it with winisd and it told me i need a port lenght of 29 inches...is this correct??