Rajini is 7 times as oldas his son .after 3 years he will be 5 times his sons age.what is rajinis present age

rajini's age - 42. let r's age be x let sons age be y x = 7y ------------eqA after 3 years x+3=r's age , y+3= sons age x+3 = 5(y+3) x+3 = 5y +15 x= 5y +12 -------eqB by elimination, X= 42