Tính nhanh

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<!--[endif]-->nhanh :
(23,4+19,5)x 7+(23,4+19,5) x 3+11
0,55 x 2 x 30+5 x 11+2,75 x 8
0,24 x 450 + 0,8 x 15 x 3 + 3 x 3 x 8
65 – 60 + 55 – 50 + 45 – 40 + 35 – 30 + 25 – 20 + 5