how can I solve this error (Unresolved reference mariuszgromada) [duplicate] // this is the main activity.kt the error is (Unresolved reference mariuszgromada) how can I solve it please help!! How do I fix this Unresolved reference mariuszgromada error, I write this code 2 times and the same error is exits and thanks for your effert anybody explain please! anybody help please! I don't know why the error is exits package com.example.calculator import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import androidx.core.content.ContextCompat...