class Calculator extends React.PureComponent {

  constructor(props) {
    super(props);
    this.state = {
       result: 0
    };
  }

  subtract = (a,b) => {
    return a - b;
  }

  add = (a,b) => {
    return a + b;
  }

  render(){
    return <p>{this.add(5,5)}</p>
  }
}