a,  49× (37 +25) + 62 × (121 -70)

49 × (37 +25 ) +62 × ( 121 – 70 )

                           =49 × 62 + 62 × 51                              

                           = (49+51) ×62                                      

                           = 100 × 62                                          

                                = 6200