This answer is really backwards for one of the changes. Remember that in a direct proportion, such as volume/temperature or pressure/temperature, when one of the values is increased, the other value must be also increased by the same amount. Think of a normal fraction 1/2 = 0.5. If you increase the 1 to 2 then the 2 must be increased to 4 to maintain the value of 0.5. If you use this simple example as a memory tool, direct proportions are easy. Both the pressure and the volume are related to the temperature by a direct proportion.