Tính (theo mẫu) :Mẫu:5 × 4 − 9 = 20 − 9 = 11 a) 5 × 5 − 10 = ..... = .....b) 5 × 7 − 5 = ..... = .....c) 5 × 9 − 25 = ..... = ......d) 5 × 6 − 12 = ...... = ......