Unsure of what error message is telling me...

Hi, I have only recently started to learn how to code this Arduino processor for the purpose of building a solar tracker. I am using an Arduino Uno revision 3, the error is located where I marked error here and the error message is:
Arduino: 1.8.7 (Windows 10), Board: “Arduino/Genuino Uno”

C:\Users\Tommy\Documents\Arduino\sketch_oct28b\sketch_oct28b.ino: In function ‘void loop()’:

sketch_oct28b:28:29: error: expected primary-expression before ‘>=’ token

while (servoSet <=140 && >=15) { // if so, send panels back to east for the sunrise

^

exit status 1
expected primary-expression before ‘>=’ token

This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.

My code is:

#include <Servo.h>
Servo servo;   // Create a servo object to control the servo
int eLDRPin = A0; // Assign pins to the LDR's
int wLDRPin = A1;
int eastLDR = 0; //Create variables to store to LDR readings
int westLDR = 0;
int difference = 0; //Create a variable to compare the two LDR's
int error = 10;  // Variable for is there is a noticable difference between the tow LDR's
int servoSet = 130; //Variable for position of servo - will be different for each device
void setup() {
 servo.attach(9);   //attaches the servo object to PWM pin 9
 Serial.begin(9600); 
}
void loop() {
 eastLDR = analogRead(eLDRPin); //Read the LDR values
 westLDR = analogRead(wLDRPin);
 if (eastLDR < 400 && westLDR < 400) {  //Check to see if there is low light on both LDR's
   while (servoSet <=140 && >=15) {     // if so, send panels back to east for the sunrise     //*error here*
     servoSet ++;
     servo.write(servoSet);
     delay(100);
   }
 }
 difference = eastLDR - westLDR ; //Check the difference 
 if (difference > 10) {          //Send the panel towards the LDR with a higher reading
   if (servoSet <= 140) {
     servoSet ++;
     servo.write(servoSet);
   }
 } else if (difference < -10) {
   if (servoSet >= 15) {
     servoSet --;
     servo.write(servoSet);
   }
 }
 Serial.print(eastLDR);      //Serial monitor can be useful for debugging/setting up
 Serial.print("   -   ");    //Use it to see if your LDR's are noticeably different when
 Serial.print(westLDR);      //They have equal light shining on them, if so, correct with the error value
 Serial.print("   -   ");
 Serial.print(difference);   
 Serial.print("   -   ");
 Serial.print(servoSet);     //Fine tune the servo settings, to maximise swing available
 Serial.print("   -   ");
 Serial.println(".");
 delay(100);}

Any help would be greatly appreciated!

s1865238:
sketch_oct28b:28:29: error: expected primary-expression before ‘>=’ token

while (servoSet <=140 && >=15) { // if so, send panels back to east for the sunrise

try changing this to

while (servoSet <=140 && servoSet>=15) {

and compile again

That worked! Thanks for your help!