CS1525 Unexpected symbol '=', HELP!!!

With this code,

using UnityEngine;

using System.Collections;



public class PainSound : MonoBehaviour {



	public AudioClip whenHurt;

	private AudioSource source;

void Awake () {
		source = GetComponent<AudioSource>();
	
	}
	

void Update () {
	
	}
void OnCollisionEnter (Collision coll)
		 {
		if (coll.relativeVelocity.magnitude > 30f && other.tag = "projectile" || other.tag = "car")
		source.PlayOneShot(whenHurt,1F);
		}
}

I get CS1525, Unexpected symbol ‘=’. Why?

I need help urgently, project is due soon!

Here other.tag = "projectile" and other.tag = "car" will always be true. Use ==

An if statement equals operator is “==” not “=”