a)

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b)

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a)

a) Cách 1: 5 × 4 + 8 × 4

              = 20 + 32

              = 52

Cách 2: (5 + 8) × 4

           = 13 × 4

           = 52

b)

b) Cách 1: 4 × 6 + 6 × 6

           = 24 + 36

           = 60

Cách 2: (4 + 6) × 6

           = 10 × 6

           = 60