How can I enable a button if in another component form they gave submit? Angular 2, Material

Hi guys I have two components in angular 2 one component A where I have a button and component B where I have a registration form, now how can I validate the button in component A so that it appears when the component B submit has been successful and keep it hidden if the submit has not been executed? Note but they are two different components A and B

A component code .html

<div>
<button md-mini-fab color="warn" class="flotante mr-1" ><md-icon>add</md-icon></button>
</div>

B component code .html

<form class="pt-1" [formGroup]="altaForm" (ngSubmit)="onSubmit($event)">
            <div class="pb-1">
                <md-select placeholder="Seleccione un producto" id="id" formControlName="id" class="full-width" [(ngModel)]="new.idproducto">
                    <md-option *ngFor="let med of tools" [value]='med.id'>{{med.tool}}</md-option>
                </md-select>
              </div>
            <div class="pb-1">
                <md-form-field class="full-width">
                    <input mdInput type="number" min="1" name="cantidad" placeholder="Cantidad (Minimo: 1)" formControlName="cantidad">
                </md-form-field>

            <div class="card-title-text center">
                <div class="">
                    <span fxFlex></span>
                    <button type="submit" md-mini-fab class="mat-primary" [disabled]="altaForm.invalid"><md-icon>send</md-icon></button>
                </div>
            </div></form>

and in the .ts of component B

onSubmit(event: Event) {
     event.preventDefault();

    this._addService.newTool(this.new.id, this.new.cantidad).subscribe(
       (data) => {
         console.log('agregado');

      },
      err => {
          console.error(err);

       },
       () => {

       }
     );
    }