How to sum selection multi option?

HTML:
Food

  <ion-select multiple="true" cancelText="Close" okText="Okay!" [(ngModel)]="signup.state"

    (ionChange)="getcitylist($event)" placeholder="Please Select ">


    <ion-select-option *ngFor="let state of statelist" [value]="state.state_name">

      {{state.state_name}}

    </ion-select-option>

  </ion-select>

TS:

signup = {

state: ''

}

statelist = [{

state_id: 1,

state_name: 'Stir-Fried Pumpkin',

state_cal: 130

}, {

state_id: 2,

state_name: ' Thick Noodle Dish',

state_cal: 110

}, ]