Don't use tables of the same size: 1/3 + 1/4 = 2/X There would be no confusion as to what X should be. And as someone else said, use units: 1/3 of table A +

Don't use tables of the same size: 1/3 + 1/4 = 2/X There would be no confusion as to what X should be. And as someone else said, use units: 1/3 of table A + 1/4 of table B = 2/7 of both tables.