constructor() {

    let a = int(random(10, 49));

    let b = int(random(10, 49));

    this.q = new Question(107, 213, 50, 2, a, b);

    this.a1 = new Answer(250, 71, 50, 2, a + b - 10);

    this.a2 = new Answer(321, 71, 50, 2, a + b);

    this.a3 = new Answer(392, 71, 50, 2, a + b + 10, 1);

    this.indicated = false;

  }

  update() {

    [this.q, this.a1, this.a2, this.a3].forEach(function(e) {

      e.update();

    })

  }

  display() {

    [this.q, this.a1, this.a2, this.a3].forEach(function(e) {

      e.display(color(255, 215, 0), color(31));

    })

  }

  to_delete() {

    return this.q.to_delete();

  }

  check_answer(x) {

    if (!this.indicated) {

      let right = this.a2.intersect(x);

      let ra1 = this.a1.intersect(x);

      let ra3 = this.a3.intersect(x);

​

      if (right || ra1 || ra3) {

        this.indicated = true;

        if (ra1) this.a1.indicate(2);

        if (right) this.a2.indicate(1);

        if (ra3) this.a3.indicate(2);

      }

​

      return right;

    }

    return false;

  } 

  intersect(y) {

    let p = this.q.get_y();

    return (p[0] <= y && p[1] >= y);

  }

}