chieu dai gap 2 lan chieu rong thi chieu dai la 2 phan ,chieu rong la 1 phan.
tong so phan bâng nhau la :2+1=3(phan)
Chieu dai la:60:3*2=40(m)
Chieu rong la:60-40=20(m)
Dien tich mieng dat hinh chu nhat do la:40*20=800(m2)
dien tich de xay nha la:800:100*15=120(m2)