How to control the particular value of the different mapping nodes So I want to control the rotation of y axis of both the mapping nodes using a single value/node in such a manner that for every increase in 1 degree in the first mapping node ( the above node) the second mapping node(the below one)shall increase by 90 degree.
Is it possible by using nodes/drivers??
You can use this node setup :

The input value (in degrees) is converted to radians then mapped to the Z value of a XYZ Vector. Then it's plugged into one of the mapping nodes on one side, and scaled on the other side then plugged in the other mapping node.