Plausible class

public class Fraction {

  private int numerator;
  private int denominator;
  
  public Fraction(int numerator, int denominator) {
    this.numerator = numerator;
    this.denominator = denominator;
  }
  
  public Fraction add(Fraction f) {
    
    int denominator = this.denominator * f.denominator;
    int numerator = this.numerator * f.denominator + f.numerator * this.denominator;
    
    return new Fraction(numerator, denominator);
  }
  
  public boolean equals(Object o) {
    Fraction f = (Fraction) o;
    return this.numerator / (double) this.denominator 
      == f.numerator / (double) f.denominator;
  }
    
}