Question

a) Số?

b) Tính

4 – 1 – 1                                    7 – 1 – 2

Answer 1

a)

Answer 2

b)

4 – 1 – 1 = 3 – 1 = 2                                                             

7 – 1 – 2 = 6 – 2 = 4

Answer 3

4