Set secondary dropdown to blank when primary one is blank

[SharePointDev12]

There are 2 dropdowns in the form and there is no relation between them. First I will select the first drop-down value next second dropdown value, again if I change first dropdown to blank value second drop-down should go blank. How to achieve this?

[BrianS]

I'm not sure if you want to set the second one blank ONLY if the first is set to Blank or if the first one is changed at all after the second is set. 

If you want the latter functionality, set a variable in the Reset property on the second dropdown (varDDreset). Put this in the OnChange of the first dropdown: Set(varDDreset,true);Set(varDDrteset,false)

If you you want the former then in the reset property of the second dropdown put this: If(IsBlank(drop1.Selected.Value),true,false)

I hand typed these so there could be slight errors