### Question:
Operacoes { public static int subtracao(int a, int b) { Operacao<Integer, Integer> subtracao = (x,y) -> { return x-y;}; return subtracao.operar(a,b); }  static int soma(int a, int b); static int subtracao(int a, int b); static int multiplicacao(int a, int b); static int divisao(int a, int b);  }### Answer:
@Test public void subtracaoTest() { assertTrue(Operacoes.subtracao(10, 15) == -5); assertFalse(Operacoes.subtracao(10, 15) == 25); }