AB上D點,AD:AB=1:3,BC上E點,BE:BC=1:4,CA上F點,CF:CA=1:5,S△DEF=19,求S△ABC?

AB上D點,AD:AB=1:3,BC上E點,BE:BC=1:4,CA上F點,CF:CA=1:5,S△DEF=19,求S△ABC?

45.6