А) 670+210:7-50
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1. 210:7 = 30
2. 670+30 = 700
3. 700-50=650.
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670+210:7-50=650
б) (520-500)*5:20
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1.) 520-500=20
2.) 20*5=100
3.) 100:20=5
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(520-500)*5:20 = 5