Question

[cô gái lạnh lùng]

mot can phong hinh chu nhat co chieu rong la 5m va chieu dai la 9m.de lat nen gach men,tren thi truong co 3 loai gach men hinh vuong voi kich thuoc tung loai nhu sau:

• loai thu nhat co canh la 30cm
• loai thu 2 co canh la 40cm
• loai thu 3 co canh la 40cm

a,muon lat kin nen can phong tren bang cung 1 loai gach sao cho khong phai cat bat cu 1 vien gach nao thi phai chon loai gach nao trong 3 loai gach tren? vi sao? (cac vien gach duoc lat lien voi nhau,khong co mach ho)

b,tinh tong so vien gach can dung theo loai da chon o cau a