handler

  handleChange = (e) => {
    const { name, value } = e.target
    this.setState((prevState, props) => ({
      [name]: value,
    }));

    const lbm = this.state.kg -(this.state.kg * (this.state.fp / 100))
    const bmr = 370 + (21.6 * this.state.lbm)
    this.setState((aprevState, props) => ({
      lbm,
      bmr
    }));
  }