cost price of 20 tables is 120000 rs
so cost of 1 table 120000/20=6000 rs
let selling price of 1 table is x rupees
selling price of 4 tables is 4x rupees according to question profit equal to the selling price of 4 tables
so profit =4x
now we know SP-CP=profit
or 20x-120000=4x
or 16x=120000
or x= 120000/16=30000/4=7500 rupees
so sp of 1 table is 7500 rupees