The pressure of a sample of gas is dependent upon the Kelvin temperature of the gas. Increasing the Kelvin temperature increases the pressure. The two quantities are directly proportional to one another. The ratio of Pressure/Temperature remains constant. So if you know the P/T ratio for one state of the gas, you can use the ratio to determine the pressure of the gas for a different temperature. Similarly, you can find the temperature requied to produce a different pressure.
 

One characteristic that we observe of a sample of gas with a varying temperature and a constant volume is that the ratio of the pressure-to-temperature is the same value for varying temperatures. Even though the temperature changes, the ratio of pressure to temperature remains constant. This behavior can be used to complete the table.

The pressure and temperature are known for the first row of the table. They can be used to determine the P/T ratio. We will refer to the result as k. Once determined, the remaining rows of the table can be filled in using the mathematical statement 

P/T = k

where k is the constant from the first row calculation. Since one of the two gas variables is known for all subsequent rows, the other gas variable can be calculated using the above equation.