Question

joao recebeu sua mesada no sábado. Nomesmo dia, gastou 2/5 e, no domingo, 1/3. Para o resto de semana, joao ficou com apenas R$100,00. Calcule o valor da mesada de Joao?

Answer 1

      A mesada, M, é formada por 
          - o que gasta
          - o que ficou
                                 GASTA
                                    mesmo dia = (2/5)M
                                    domingo = (1/3)M
                                          total = 2/5 + 1/3
                                                  = (2x3 + 1x5)/15 [15 = mmc(5,3)]
                                                  = (6 + 5)/15
                                                  = (11/15)M
                                 FICOU
                                    100,00
     Então
                                (11/15)M + 100 = M
                       multiplicando todo por 15
                                11M + 1500 = 15M
                                            1500 = 15M - 11M
                                             1500 = 4M
                                                  M = 375
                                                             A MESADA É DE RS 375,00