Can't resolved 'rxjs/Rx' in tutorial example - angular5

Question

The angular-cli version is 6.0.8 and the rxjs version is 6.3.3.
I'm following a tutorial and getting the error: Can't resolve 'rxjs/Rx'. How do I go about resolving the error? Is there a way that I can use a previous version of the rxJS?
Here is the code:
service.ts
import { Injectable } from '#angular/core';
import { HttpClient } from '#angular/common/http';
import { Observable } from 'rxjs';
#Injectable()
export class Service {
constructor(private _http: HttpClient) {
}
getPosts(): Observable<any> {
return
this._http.get("http://jsonplaceholder.typicode.com/posts");
}
}
app.module.ts
import { BrowserModule } from '#angular/platform-browser';
import { NgModule } from '#angular/core';
import { AppComponent } from './app.component';
import { HttpClientModule } from '#angular/common/http';
import { Service } from './service';
#NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
HttpClientModule
],
providers: [HttpClientModule, Service],
bootstrap: [AppComponent]
})
export class AppModule { }
app.component.ts
import { Component, OnInit } from '#angular/core';
import { Service } from './service';
import 'rxjs/Rx';
#Component({
selector: 'app-root',
template: `
<ul>
<li *ngFor="let post of _posts">
<b>{{post.title}}</b> {{post.body}}
</li>
</ul>
<div *ngIf="_error">
Error: {{_error.status}}:{{_error.statusText}}
</div>
`,
styles: ['div {font-size:20px;padding:5px;background-
color:red;color:white}']
})
export class AppComponent implements OnInit {
_posts = [];
_error;
constructor(private _service: Service) {}
ngOnInit() {
this._service.getPosts()
.subscribe(
response => {
this._posts = response;
},
error => {
this._error = error;
}
);
}
}

Answer 1

As you are using Rxjs V6 and Above. Rxjs made the path based import optional.
import 'rxjs/Rx';
Why you need this import?. Not seeing RX is used in your component. Please remove and try if not required.

Answer 2

Make sure that rxjs-compat library also included in pakage.json file