GPS Phone Location to Arduino using Bluetooth

Hi,
I am trying to send my phone location to arduino using bluetooth. I am able to connect to the app and I can see lat and long on the app but it displays as all zeros when receiving the output on arduino. Below is my code. I think it is because the coordinates are being sent as two separate texts instead of together. I am not sure how to fix this.

String a;

void loop()

{

while(bluetoothSerial.available()) {

a= Serial.readString();// read the incoming data as string

Serial.println(a);

}